HomeMy WebLinkAboutAppendix H-Hydrologic Resources StudiesAPPENDIX H
Hydrologic Resources Studies
H.1 – Preliminary Hydrologic and Hydraulic Calculations
H.2 – Existing Froom Creek Hydrologic Analysis
H.3 – Preliminary Sediment Transport Analysis and
Calculations
Froom Ranch Specific Plan Project
Draft EIR
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APPENDIX H.1
Preliminary Hydrologic and Hydraulic Calculations
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PRELIMINARYHYDROLOGIC AND HYDRAULIC CALCULATIONS
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Date: 7-14-2017; Revised 31; Revised 02-22-2019
Prepared by RRM Design Group
Prepared for John and Susan Madonna Trust and Villaggio
Communities
CREATING
ENVIRONMENTS
PEOPLE
ENJOY®
Table of Contents
1. Hydrologic and Hydraulic Analysis Page No.
1.1: Introduction 1-1
1.2: Location Map / Description 1-1
1.3: Executive Summary 1-2
1.4: Watershed Description 1-2
1.5: Methodology 1-3
1.6: Hydrologic Analysis 1-4
1.7: Hydraulic Analysis 1-8
1.8: Risk Assessment / Impacts Discussion 1-11
1.9: Unusual or Special Conditions 1-11
1.10: Conclusions 1-11
2. Geomorphic Evaluation
2.1: Introduction 2-1
2.2: Physical Setting 2-1
2.3: Existing Froom Creek Corridor Conditions 2-1
2.4: Proposed Froom Creek Corridor Conditions 2-2
2.5: Conclusion 2-4
3. Froom Creek Restoration Program
3.1: Introduction 3-1
3.2: Froom Creek Restoration Objectives 3-1
3.3: Froom Creek Planting Goals 3-1
3.4: Froom Creek Enhancement Plan 3-2
3.5: Froom Restoration Plan 3-4
3.6: Froom Restoration Plant List 3-5
3.7: Froom Restoration Sections 3-6
3.8: Conclusion 3-12
List of Tables:
Table 1-1: Froom Ranch SP Development Areas - Storage Volume 1-10
Table 1-2: Offsite Development - Storage Volume 1-10
List of Figures:
Figure 1-1 Existing location of Froom Ranch Specific Plan Area 1-1
Figure 1-2: Froom Creek Historical Alignment 1-3
Figure 1-3: Existing Drainage Conditions 1-4
Figure 1-4: Proposed Drainage Conditions 1-7
Figure 2-1: Proposed Froom Creek corridor concept 2-3
Figure 3-1: Froom Creek enhancement concept 3-3
Figure 3-2: Froom Creek restoration plan 3-4
Figure 3.3: Section A-1 3-7
Figure 3.4: Section A-2 3-8
Figure 3.5: Section A-3 3-9
Figure 3.6: Section B 3-10
Figure 3.7: Section C 3-11
Appendices:
Appendix 1: HEC - RAS Summary Table and Cross Sections
Appendix 2: Existing Tributary Area
Appendix 3: Proposed Peak Flow Tabulation
Appendix 4: Soils Information
Appendix 5: Firm Maps
Appendix 6: City of San Luis` Obispo Storm Water Control Plan Application
Appendix 7: Cleath-Harris Groundwater Report
Appendix 8: HEC – HMS Hydraulic Modeling Results
Chapter 1
Hydrologic and Hydraulic Analysis
1-1
1. Hydrologic and Hydraulic Analysis
1.1 Introduction and Background
This report was prepared to analyze the hydrologic and hydraulic data for the proposed Froom Ranch
Specific Plan project and adjacent tributary runoff. The Froom Ranch Specific Plan is primarily a Senior
housing development project with a mix of commercial and residential uses near the existing Irish Hills
Plaza.
1.2 Location Map/Description
The Froom Ranch property consists of approximately 109.7 acres. The site is composed of two parcels,
located immediately west of Los Osos Valley Road within the County of San Luis Obispo’s jurisdiction, and
adjacent to the City limits (APNs 067-241-030 and 067-241-031).
Figure 1-1: Existing location of Froom Ranch Specific Plan Area
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The site is characterized by relatively flatter grassland areas which transition to steeper slopes before
approaching City open space property at the base of the Irish Hills. The bulk of the property is
undeveloped but includes historical ranch and dairy structures on part of the site directly to the south of
the Home Depot retail store which is included in the adjacent Irish Hills Plaza. This area of the property is
currently used as an office (main ranch house) and equipment storage yard to support John Madonna
Construction Co. Inc. The site also includes unimproved roads, staging and materials storage, a quarry
area, and a storm water detention facility for the neighboring Irish Hills Plaza (see Figure 1-1).
1.3 Executive Summary
The following sections of this report describe the proposed project and how the proposed condition
affects the internal and surrounding hydrological elements. The project is compliant with following
design guidelines:
· The project complies with the San Luis Obispo Drainage Design Manual
· The project complies with the San Luis Obispo Waterway Management Plan
· The project complies with the Central Coast Regional Water Quality Control Post Construction
Requirements
· The project complies with the FEMA Floodplain Management guidelines
Additionally, the project results in the following conditions:
· The project does not cause significant negative downstream effects
· The project does not negatively affect adjacent or on-site wetland habitat
· The project does not negatively affect groundwater resources
1.4 Watershed Description
The site is bisected by natural drainages in the northeastern flank of the Irish Hills. The existing Froom
Creek corridor traverses the Specific Plan area in a mostly north to south direction and joins San Luis
Obispo Creek south of the Specific Plan area before flowing towards the Pacific Ocean in Avila Beach.
Small areas of wetland habitat occur along the unnamed tributary drainages to Froom Creek in the
southwestern area of the site, and a larger contiguous wetland area exists in flat grassland areas where
surface and subsurface water is impounded by Los Osos Valley Road and Calle Joaquin. Froom Creek is a
relatively narrow channel with incised banks that bisect the Specific Plan area in a north to south direction,
and ultimately flows beneath U.S. Highway 101 via two concrete box culverts, heading to its confluence
with San Luis Obispo Creek. As stated in the Los Osos Valley Road and US101 Interchange Improvement
Project, the box culverts do not support storms above the 10-year event and spill over the top of Calle
Joaquin at the box culverts. Due to the lack of dominant wetland vegetation within or adjacent to the
channel, Froom Creek was classified as non-wetland waters of the U.S. and State of California subject to
U.S. Army Corps of Engineers, Regional Water Quality Control Board and California Department of Fish
and Wildlife jurisdiction pursuant to the Clean Water Act (Sections 401 and 404) and California Fish and
Game Code (KMA, 2015).
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The Specific Plan area includes about 7.25 acres of jurisdictional wetland habitat located on the
southwestern part of the site near Los Osos Valley Road and Calle Joaquin. These wetlands are partially
within an existing open space easement.
Froom Creek has a history of periodic flooding with estimated overbank flows occurring every five to six
years (Balance Hydrologics, 2005). Studies have shown that while some overbank flow contributes to
wetland habitat along Calle Joaquin, the primary function of Froom Creek appears to be groundwater
recharge, and subsurface maintenance of the Calle Joaquin wetland area (see Figure 1-1). Historically,
Froom Creek had a different alignment from what currently exists on the site today (see Figure 1-2).
Based on review of an 1895 U.S. Geological Survey topographic map, the creek channel took a more
direct northeasterly path as it exited the Irish Hills and ultimately connected with Prefumo Creek and
San Luis Obispo Creek.
In consideration of the unique characteristics of the Specific Plan area, a program has been developed to
restore Froom Creek closer to its historic alignment on the property, keeping its current hydrologic
connection to San Luis Obispo Creek and connection to the wetlands habitat near Calle Joaquin.
Figure 1-2: Froom Creek Historical Alignment
1.5 Methodology
The project site has been analyzed using several City of San Luis Obispo and FEMA approved methods
including: HEC-HMS, HEC-RAS, The Rational Method, and the SCS Runoff Curve Number method. These
methods combine in a variety of ways to present the information and tables found in this report. The
inputs and assumptions used in each of these methods are included in the corresponding appendix.
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Figure 1-3: Existing Drainage Conditions
1.6 Hydrologic Analysis
The Froom Ranch Planning Area is located within the watershed of Froom Creek which is a relatively small
watershed that originates in the Irish Hills.
Existing Drainage Conditions: The existing drainage conditions for the Froom Creek Specific Plan Area
include Froom Creek flows across the site in a north to south trajectory ultimately passing through two
box culverts beneath Calle Joaquin and US 101 before its confluence with San Luis Obispo Creek. These
culverts do not have adequate capacity to pass the 10-year event for the watershed it serves (LOVR/US101
Interchange Improvement Project 2010). Furthermore, the confluence of the San Luis Obispo Creek (a
major waterway) and East Fork drainage immediately downstream of the culverts causes a tailwater
condition limiting the ultimate efficacy of the existing Froom double box culverts. There are three small
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ephemeral tributaries to Froom Creek in the southwestern portion of the site. In addition, there is a man-
made drainage ditch that parallels Los Osos Valley Road (LOVR).
An approximately 3.2-acre detention basin currently exists in the southeastern grassland area of the site
to receive runoff from the adjacent Irish Hills Plaza development fronting LOVR. It consists of a de-siltation
forebay which retains and infiltrates up to 2-year rain events, a main basin and spillway, and was sized to
contain runoff from the Irish Hills Plaza. This basin releases water exceeding the 2-year event to the LOVR
drainage ditch by a storm drain and swale. During large storm events, the main basin discharges runoff
into the wetland area along Calle Joaquin via a concrete spillway. A report conducted by Cleath-Harris
Geologists studying the groundwater (provided in Appendix 7) finds that the wetlands adjacent to Calle
Joaquin and the Irish Hills detention basin is primarily fed by upward leakage of seasonally shallow
groundwater. The report continues to find (based on a 2004 report from Balance Hydrologics) that Froom
Creek overflow in high storm events happens infrequently and “may not be sufficient to sustain both
seasonal and perennial wetlands”. Furthermore, the Irish Hills basin forebay does not source the adjacent
wetland in small events as the forebay subdrains do not connect to the outer perimeter drains. The
forebay’s primary function is to infiltrate runoff directed into the forebay by the diversion weir contained
in the upstream manhole.
The existing Froom Creek channel alignment comes down from the hillside easterly where it makes
approximately a 90-degree turn where the channel banks recede and make way for a low-lying
meandering channel. The existing Froom Creek channel does not have adequate capacity to convey 100-
year storm events to the Highway 101 culverts and consequently overtops the existing banks and flows in
a sheet flow manner towards LOVR and Calle Joaquin (see Figure 1-3). The resulting condition is that the
low-lying area between LOVR and the Irish Hills is designated as a FEMA Flood Insurance Rate Map, Zone
A, no base flood elevation is established as shown on FIRM Map Panel Nos. 06079C1331G & 06079C1068G
(see appendix 6).
Proposed Drainage Conditions: Development of the Specific Plan area will enhance and restore the
historic Froom Creek corridor alignment and allow it to traverse future development areas. The restored
creek corridor will be enhanced with native riparian plant communities. This would increase the function
and value of the riverine system and resolve the periodic flooding issues.
The creek channel will be sized to handle up to a 100-year storm event with a minimum of one foot of
freeboard. The creek corridor is proposed to be developed in a manner consistent with the City of San
Luis Obispo Waterways Management Plan.
The San Luis Obispo Waterways Management Plan (WMP) sets forth criteria for drainage design for the
Specific Plan areas tributary to San Luis Obispo Creek. The WMP indicates that storm water detention
should be used in areas where there are downstream capacity limitations, which has been an issue in this
area of the City. As stated above in the Existing Drainage Conditions, the downstream confluence of the
San Luis Obispo Creek and the Froom drainage produces a tailwater condition. The WMP identifies this
confluence as a problem area; any delay in the peak discharge of the Froom drainage exacerbates the
1-6
existing flooding at this confluence. Appendix 8 describes this condition through modeling by the HEC-
HMS system which emulates the city-wide hydraulic process.
The drainage plan proposed for the Froom Ranch Area complies with the WMP. The restored Froom Creek
corridor conveys flows from the project and the offsite upper reaches of the existing creek to the
southeast corner of the property to connect to the existing creek bed that ultimately leads to a double
box culvert going under Highway 101. Implementation of the Specific Plan drainage program will remove
the site development areas from the FEMA flood plain. The project proposes to formalize the removal of
the project development area from the FEMA flood plain through the Conditional Letter of Map Revision
(CLOMR)/Letter of Map Revision (LOMR) process.
The proposed Froom Creek corridor includes a low flow channel throughout the reach of the channel and
a large overbank area to convey larger flows. The low flow channel will provide a meandering conveyance
designed to enhance and restore fish migration patterns on-site through stepped pools and terraces
throughout the reach. At the jurisdictional wetlands, adjacent to Calle Joaquin, the overbank area is
proposed to be flattened allowing storms larger than a two–year event to migrate into the existing
wetland to provide water to sustain this wetland.
The off-site (located on the Mountainbrook Church property) project basin which provides additional
“surge” storage for large storm events (see Figure 1-4). The existing box culverts overtop the Calle Joaquin
road immediately above the culverts during 10-year events. The proposed basin will allow for storage
enough to allow the 25-year event to pass entirely through the culverts. The 50-year and 100-year events
are prohibitively large to allow for storage during these events and overtop Calle Joaquin as safe overflow.
Appendix 8 provides HEC-HMS modeling showing these storm events and the corresponding peak flows,
high water elevations, and storage required. The basin also serves to provide storage pursuant to the post
construction requirements 3 (Runoff Retention) and 4 (Peak Management).
1-7
Figure 1-4: Proposed Drainage Conditions
1-8
1.7 Hydraulic Analysis
The Storm Water program for the Froom Ranch Specific Plan Area proposes to be consistent with the
California Regional Water Quality Control Board, Post Construction Storm Water Management
Requirements for Development Projects in the Central Coast Region and the City of San Luis Obispo
Waterways Management Plans.
The Froom Ranch Specific Plan area is segmented into varied residential densities and commercial uses.
Each of the development areas consist of one or more drainage management areas. Development areas
are accessed via public and private roads acting as a backbone circulation system for the project. A
series of drainage conveyances and low impact development and storage components, including the
restored Froom Creek corridor, serve to provide treatment, filtration and storage for the Specific Plan
Area. It should be noted that development of each land use area is conceptual at this juncture however
this report intends to provide storm water control directives to be implemented with development of
each of the land use areas as well as backbone implementation of the creek corridor, storm water
systems, storage and conveyances that will serve the specific plan area at build out. The detailed
hydraulic analysis of the drainage management areas, channel flow and storm water systems are
contained within Appendices 1 - 6 of this report. The key components of the storm water controls
addressing post construction requirements are listed below:
Restored Froom Creek Corridor: The Froom Creek corridor is a waterway conveying approximately 1088
cubic feet per second +/-(CFS) at the point of discharge through an existing double box culvert at
Highway 101. The restored creek corridor connects to the existing Froom Creek channel at the
southwesterly boundary of the project and conveys existing and proposed flows through the site to the
point of discharge at Highway 101. The design of the restored corridor includes a low flow conveyance
for storm events up to two – year flow and contains 100-year flows with a minimum of one foot of
freeboard within the proposed creek banks. A Contech pre – fabricated natural bottom culvert is
proposed in the alignment to allow roadway circulation to cross over the creek. The design of the Froom
Creek corridor effectively removes the site from the FEMA, Zone A designated flood plain. A letter of
map revision (LOMR) to remove development areas from the flood zone is anticipated to be part of the
project implementation. The proposed creek corridor provides two key overbank design features along
its reach, prior to discharge at Highway 101, one that perpetuates the existing wetland area along Calle
Joaquin and a second overbank area that allows larger flows into a proposed storage basin on the
adjacent Mountainbrook Church property. The capacity of the restored creek corridor requires bank
slope protection measures outlined in the Drainage Design Manual section 3.6. Bank stabilization
techniques will be utilized for sections of creek where flow speeds are erosive to naturally reconstructed
embankments. Such techniques include but are not limited to: live staking and willow wattling,
vegetated geogrids, live rock walls, rock slope protection, and planted gabion baskets.
Los Osos Valley Road (LOVR) ditch: The project includes a vegetated drainage ditch adjacent to LOVR
ditch to complete the alignment of the existing ditch that fronts the Irish Hills Plaza development that
conveys flows of approximately 36 CFS +/- from the Irish Hills Plaza and approximately 155 CFS+/- from
the Home Depot ditch to the Froom Creek corridor. The LOVR ditch includes a closed conduit crossing at
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the entry road to the project. The LOVR ditch provides point source water quality treatment of
development flows that are adjacent to its reach prior to entering the Froom Creek corridor. The LOVR
ditch also receives delayed flows from the Costco drainage summarized in Appendix 8.
The Home Depot ditch: The project proposes a vegetated retention basin along the northerly boundary
that conveys flows of approximately 155 CFS +/- from a natural swale located behind Home Depot to the
LOVR ditch and ultimately into the Froom Creek corridor. This ditch includes a closed conduit crossing at
the project roadway connection to the Irish Hills Plaza drive aisle. This ditch provides point source
treatment of development flows adjacent to its reach and relocates the Home Depot water quality bio
filtration component (post construction requirement #2 — see appendix 6 for storm water control plan
exhibit) from the existing position in the open space of Froom Ranch to a location adjacent to the
western boundary. This retention basin serves as water quality treatment pursuant to the state adopted
post construction requirements for water quality totaling 1.0 acre – feet of runoff treatment storage
adjacent to the westerly edge of the project. An overflow bank is provided for larger storm events
conveyed into the LOVR ditch at the northwesterly corner of the project.
Land Use Areas: Development areas within the project are required to provide point source water
quality treatment of storm water prior to discharge into the creek corridor. When a land use area is
proposed for development, each individual project will be responsible for implementation of the state’s
adopted post construction requirements 1 (Site Design) and 2 (Water Quality). The downstream basin
serves to attenuate post development flows for post construction requirements 3 (Runoff Retention)
and 4 (Peak Management).
Backbone Roads: The project proposes public and private roads that provide access to each of the land
use areas. Impervious surfaces associated with roadways incorporate vegetated swales and bio –
filtration to address point source water quality treatment prior to conveyance of runoff to Froom Creek.
Mountainbrook Church Basin: The project addresses PCR 4 peak management through use of a
proposed storm water basin located directly adjacent to the Froom Ranch Specific Plan area on the
Mountainbrook Church property. The basin is located southeasterly of the property boundary. The basin
volume is approximately 28.8 acre - feet (+/-) with a minimum of one foot of freeboard. The storage
volume meets or exceeds the Froom Ranch Specific Plan build – out PCR 4 requirement and also
includes storage volume relocated from onsite for Home Depot, Irish Hills Plaza and potential future
development of facilities on the Mountainbrook Church site. The design of the basin will promote
infiltration of runoff and provide outflow controls to attenuate existing capacity issues at the Highway
101 double box culverts.
Post Construction Performance Requirements (PCR’s) 1 through 4 for determining the post –
development runoff storage volumes and addressing water quality treatment are included in the project
storm water management program. As stated in the Land Use Area summary above PCR’s 1, 2 & 3 are
required for build-out of individual projects in each of the Froom Ranch SP development areas, PCR 4 is
addressed through use of the Mountainbrook Church basin and is summarized in the following
paragraphs with additional technical data provided in appendix 6 of this report.
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The flat areas of the site adjacent to Los Osos Valley Road lie in Watershed Management Zone (WMZ) 1.
WMZ 1 requires a 95th percentile storm volume retention. Based on review of the WMZ rainfall
mapping, the 95th percentile, 24-hour storm event is equal to 1.9 inches over the WMZ 1 development
area. The upper reaches of the planning area are identified as WMZ 9 and require 85th percentile, 24-
hour storage equivalent to 1.2 inches over the WMZ 9 development area. The Froom Ranch Planning
Area has been segmented into drainage management areas (DMA’s) that are tributary to the proposed
Froom Creek corridor. Detailed hydrologic calculations can be found in Appendices 1 - 8 of this report, a
summary of PCR 3 storage volume requirements for onsite DMA’s is listed below.
Table 1-1 identifies each of the land use areas, consistent with the Froom Ranch Specific Plan, and their
respective effective impervious area storage volume requirements dictated by the state post
construction requirement 3 to be retained and treated on each individual development area.
Drainage
Management
Area
Zoning / Land Use
Designation
Development
Area (Acres)
WMZ Retention Volume
Required (ac-ft)
Residential +
Park
R-3, Medium High
Density Residential &
Park
12.70 1/9 0.90
Commercial CR-SP, Commercial
Retail
10.07 1 1.05
Lower Villaggio R-3-SP, Medium High
Residential (Villaggio-
Life Plan Community)
26.94 1 2.32
Upper Villaggio R-3-SP, Medium High
Residential (Villaggio-
Life Plan Community)
12.53 9 0.56
Totals 62.24 4.83
Table 1-1: Froom Ranch SP Development Areas - Storage Volume
Table 1-2 lists other DDM derived basin storage volumes from offsite development areas relocated to
the Mountainbrook Church Basin for Home Depot and Irish Hills Plaza and future Mountainbrook Church
potential development (pursuant of PCR 4). PCR 2 for these areas will be located on-site near the point
of discharge on the northerly border of the site.
Offsite
Drainage Areas
Storm Water Feature Development
Area (Acres)
WMZ Storage Volume
Required (ac-ft)
Home Depot Relocated Detention
Volume
10.14 1 1.27
Irish Hills Relocated Detention
Volume
15.23 1 2.33
Mountainbrook
Church
Future development
Runoff Retention
Volume
3.67 9 0.37
Totals 32.43 3.97
Table 1-2: Offsite Development – Storage Volume
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The Mountainbrook Church basin is designed with approximately 28.8 acre – feet of storage capacity at
a water surface elevation of 104.0; the required storage volume is generated from the relocated and
future detention from Table 1-2 (3.97 ac-ft) plus the detention volume calculated from Table 1-3 (16.99)
which totals 20.96 ac-ft required. The basin has been designed to provide additional capacity for the
purposes of attenuating high flow conditions that exceed the capacity of the Highway 101 culverts (565
cfs) pursuant to the San Luis Obispo Drainage Design Manual (DDM). The DDM requires attenuation
from 2-yr through 100-yr events such that there are no significant (greater than 5% downstream
increase) downstream effects. Appendix 3 tabulates the pre-vs-post conditions and show that the
downstream effect is less than 5% with a net decrease in most storm events. The greater volume allows
the basin attenuate the high inflow with the constrained double box culvert outflow thereby reducing
flood stage elevations for the creek and along the Calle Joaquin wetland. The additional detention
storage allows higher storm events to pass through the existing double box culverts without overtopping
the above Calle Joaquin spillway. Finally, the existing hydraulically connected wetlands upstream of the
project basin provides approximately 11 ac-ft of detention.
Froom
Lower
Froom
Dev
Froom
Lower Froom Dev
Total Storage
Req'd (ac-ft)
Ex-2yr 30.133 20.454 Pro-2yr 36.251 22.909 8.573
Ex-10yr 40.954 22.874 Pro-10yr 49.941 26.289 12.402
Ex-25yr 51.175 25.161 Pro-25yr 62.137 29.206 15.007
Ex-50yr 58.985 26.908 Pro-50yr 71.165 31.333 16.605
Ex-
100yr 61.092 27.379 Pro-100yr 73.567 31.895 16.991
Table 1-3: Pre-Post storage design volumes.
1.8 Risk Assessment/Impacts Discussion
Approximately 35% of the existing Froom Ranch Specific Plan area is in a FIRM map, Zone A designation,
no base flood plain elevation. The FIRM Zone A area is in the lower flat land of the project bound on four
sides by LOVR, Calle Joaquin, the Irish Hills Plaza and the hillside terrain of the Irish Hills Natural Reserve.
Due to the very flat terrain along the LOVR corridor and along Calle Joaquin, runoff from LOVR and
overtopping of the existing Froom Creek corridor creek banks localized flooding and ponding have
historically been observed on the site. Additionally, the Highway 101 double 5’ x 5’ box culverts overtop
at the 10 - year storm event, 547 CFS (WRECO, location hydraulic study, Nov. 2010).
For the reasons stated above the project proposes to implement several flood control components key
to minimizing risk associated with potential flooding. The restored Froom Creek corridor design
proposes to convey up to 100 - year storm events within its creek banks with an additional minimum of
one foot of freeboard. The grading of the project, prior to future individual projects, proposes to raise
the elevation of the lower flat area above the projected flood stage so that finish floor elevations can
achieve a minimum of one foot above the 100 – year flood. The Mountainbrook Church overbank area
and basin are anticipated to provide better channel function and some attenuation of larger peak flows
conveyed to the Highway 101 box culverts to assist in minimizing tail - water flooding potential.
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1.9 Unusual or Special Conditions
As discussed in previous sections of this report, the Froom Ranch Specific Plan project proposes to
remove approximately 2,200 linear feet of the existing, relocated Froom Creek corridor and restore it to
its approximate original location. The existing alignment does not provide adequate capacity for large
storm events and does not provide an aquatic or riparian habitat. The new alignment provides a unique
opportunity to recast the creek in a way that will restore it to a vibrant creek corridor and enhanced fish
habitat. The proposed Froom Creek alignment will require permitting through the Army Corps of
Engineers, California Fish and Wildlife, the Central Coast Regional Water Quality Control Board and
other jurisdictional agencies. Other requirements include removal of the site from the FEMA FIRM map
Zone A through processing of a Conditional Letter of Map Revision (CLOMR) and a final Letter of Map
Revision (LOMR).
1.10 Conclusions
The Froom Ranch Specific Plan project is a comprehensive plan to create a special environment for
people to enjoy. It is included in the City of San Luis Obispo’s Adopted Land Use and Circulation Element
(2014) as a desired annexation area with development anticipated. The project site provides challenges
and opportunities in implementing a storm water program that balances limited development of the site
(50% open space required), while enhancing the environmental elements. The findings and conclusions
of this report are that restoring the Froom Creek corridor can be accomplished in a manner that meets
environmental and flood control goals for the City of San Luis Obispo. The project as designed intends to
comply with the City of San Luis Obispo Waterways Management Plan and the Central Coast Regional
Water Quality Control Board Requirements for Development Projects in the Central Coast Region
(Resolution No. 2013-0032). The project as designed accommodates new development without flood
risk and removes the site from FEMA FIRM Map Zone A. And lastly, the project as designed, intends to
implement a series of pipes, channels and low impact design features that comply with the City of San
Luis Obispo standards for capacity and function.
Chapter 2
Geomorphic Evaluation
2-1
2. Geomorphic Evaluation
2.1 Introduction
The Froom Ranch Specific Plan Area proposes to restore the Froom Creek corridor to its approximate
original alignment, an important component of the restoration effort includes evaluation of the existing
creek corridor constraints and physical nature and provides discussion of the proposed creek corridor
design as it relates to the development setting, the opportunities for restoration and the anticipated
geomorphic controls.
2.2 Physical Setting
Froom Creek is a tributary to San Luis Creek, it is approximately 1.5 miles long and runs east to west from
its upper reach in the Irish Hills Natural Reserve hillside and then turns south to the point of confluence
with San Luis Creek. Froom Creek consists of two distinct segments; the lower reach (approx. 4,200 linear
feet), which has been significantly altered over time and traverses the Froom Ranch Specific Plan area to
a double box culvert discharge conveyance which outlets into San Luis Creek and the upper reach (approx.
3700 linear feet) within the City Irish Hills natural reserve which remains in its existing condition upstream
from the connection with the restored alignment onsite.
2.3 Existing Froom Creek Corridor Conditions
The upper reach of Froom Creek, west of the project site, is to remain intact and exists as an
intermittent stream. The creek varies in width and contains pools along the creek corridor, significant
vegetation and is considered adequate habitat for steelhead. The upper reach dissipates as it enters the
site into the altered lower reach. The lower reach of Froom Creek which traverses the site is an incised
channel confined by a man – made earthen berm along a portion of the eastern bank of the creek. The
creek bed is generally dry and consists of rock washed down from the upper reach of the channel and is
devoid of significant vegetation. Soils within the lower reach Froom Creek within the project boundary
generally consist of Obispo - Rock outcrop in steeper zones of the creek bed, consisting of black clay to a
depth of approximately 18 inches underlain by serpentine rock, and Riverwash consisting of excessively
drained, water deposited sand, loamy sand with gravel and cobbles (KMA – Delineation of waters of the
U.S., August 2015). Areas of the lower reach channel do not contain large storm events within the creek
banks and are prone to moderate erosion and bank cutting due to high velocities during larger storm
events. The lower reach does not contain wetland vegetation within or adjacent to the channel.
2-2
Photograph of the existing lower reach Froom Creek corridor (Date: January 20th, 2015)
2.4 Proposed Froom Creek Corridor Conditions
The proposed restored Froom Creek corridor joins the existing creek at the northwest corner of the
Specific Plan area where it will flow east through the project site toward LOVR before it curves to
parallel the Calle Joaquin road corridor on the border of the wetland area. The restored creek then
intersects with the original creek bed at the southeast corner of the property. The restored Froom Creek
lower reach is a unique opportunity to provide a healthy riparian corridor across the Specific Plan area in
replacement of the degraded existing corridor.
The restored Froom Creek corridor design, within the project area boundary will be constructed with
imported fill and subject to geotechnical inspection during placement of materials. The hydraulic design
criteria are based on the City of San Luis Obispo Waterway Management Plan. Detailed hydraulic
analysis of the channel can be found in Appendices 1-3.
A summary of the key hydraulic objectives and design goals are:
1.A low flow channel to handle up to two - year storm events.
2.Varying embankment slopes (maximum 2.5:1) to enable plant shading and minimize mass waste.
3.Upstream sediment capture within new development areas.
4. 100 – year storm containment within the creek corridor with one foot of freeboard.
2-3
5. Non – erosive velocities (approx. 2 – 8 feet per second) to minimize potential for undercutting.
6. Armoring of slope banks and culvert locations, in select locations where necessary, will provide
openings to allow fish passage.
7. Intersecting tributary ditches or stream beds will be stepped to contain and direct fish within
the main Froom Creek corridor.
In addition to the hydraulic design features of the channel, the restored Froom Creek provides new
riparian and steelhead habitat based on the City of San Luis Obispo’s Waterway Management Plan and
the California Salmonid Stream Habitat Restoration Manual including:
1. A natural bottom utilizing existing boulders and cobbles that are relocated from the existing
creek corridor.
2. A low-flow meandering channel that allows for pooling, deposition, and load transport.
3. Incorporate stepped pools and terraces to control fish migration patterns.
4. Overbank areas to provide runoff flow into adjacent existing wetlands.
5. Control of light reaching the stream bed.
6. Natural litter and invertebrate fall.
7. Woody debris components.
Figure 2-1: Proposed Froom Creek corridor concept
2-4
More detailed information regarding the Froom Creek Restoration Program can be found in Section 3 of
this report.
2.5 Conclusion
The Froom Creek lower reach located in the Froom Ranch Specific Plan area is currently in a degraded
condition and has been altered several times with the ranching uses on the property. The restored
Froom Creek corridor meets the objectives of low velocity, minimal sediment transport, low impact
design and conforms to the City of San Luis Obispo Waterway Management Plan and the California
Salmonid Stream Habitat Restoration Manual.
Chapter 3
Froom Creek Restoration Program
3-1
3. Froom Creek Restoration Program
3.1 Introduction
The Froom Creek restoration program is based on the initial grading models, prepared in cooperation
with City and other responsible agencies, for the new alignment as shown on the vesting tentative map,
and is subject to modification during final design. The restoration program focuses on preparation of
preliminary recommendations for creek cross sections, planting schemes and objectives for the design.
3.2 Froom Creek Restoration Objectives
The creek restoration objectives for the Froom Creek corridor are to develop three zones for
restoration:
• Riparian Buffer: Zone between the top of bank and edge of setback. A 35’ setback is
utilized for Froom Creek, and a 20’ setback for the drainage ditch along Los Osos Valley
Road. The zones are envisioned to be planted with trees at an average of 50’ on center,
and shrubs at an average of 5’ on center. This zone is proposed to be drip irrigated.
• Channel Banks: Zone between the top and toe of bank. These zones are envisioned to
include herbaceous species that can tolerate seasonal undulation, and planted at an
average of 3’ on center spacing. This zone is proposed to be spray irrigated.
• Channel Bottom: Zone below the toe of bank. This area is envisioned to include
herbaceous wetland species planted at an average of 3’ on center spacing. This zone will
not be entirely planted, but is approximated to be 30% of the bottom area and expected to
naturalize and fill the flat bottom areas. This zone is proposed to be temporarily spray
irrigated to establishment.
3.3 Froom Creek Planting Goals
The planting goals for the Froom Creek corridor were developed utilizing the City of San Luis Obispo’s
Waterway Management Plan, Volume III, Drainage Design Manual dated February 2003 as a guideline
for creek design, cross - sections and plant list.
The study assumes that plants used for creek restoration will meet the following parameters:
• Native non-invasive riparian species
• Mix of evergreen and deciduous varieties
• Vegetation located in naturalistic groupings
• Planting will include plant mitigation areas
• Vegetation will tolerate recycled water for irrigation
• Biotechnical erosion control methods will be utilized
3-2
• Adjacent existing wetland will be enhanced
3.4 Froom Creek Enhancement Plan
The conceptual enhancement plan shows the general planting concepts for the Riparian Buffer, Channel
Bank, and Channel Bottom zones. Froom Creek restoration will meet the following parameters:
• The Channel Bottom contains a low-flow channel that allows for pooling, deposition and
load transport.
• Stepped pools and terraces will be used to control fish migration patterns.
• Existing boulders and cobbles will be relocated from the existing creek corridor.
• Project will explore opportunities in upper reaches of Froom Creek to enhance fish habitat.
• Creek enhancements will be managed and monitored.
• A riparian buffer with pedestrian amenities should be included.
3-3
Figure 3.1: Froom Creek enhancement concept
3-4
3.5 Froom Creek Restoration Plan
The plan below demonstrates the realigned Froom Creek corridor with the proposed restoration
enhancement areas. Consistent with the City of San Luis Obispo Creek Setbacks regulations (Chapter
17.16.025), the plan shows a 35’ setback along the Froom Creek corridor, and a 20’ setback along the
Los Osos Valley Road drainage channel. The realigned creek corridor is proposed to run adjacent to the
existing wetlands, and utilize this area for drainage during peak flows. All storm water will be treated
prior to entering the creek corridor.
Figure 3.2: Froom Creek restoration plan
3-5
3.6 Froom Creek Restoration Plant List
The following list of plants is preliminary, and intended to provide the initial planting recommendations
and a potential list of species. Additional species may be included and list revised as the project design
is finalized.
Trees: Trees are proposed to primarily 15 gallon containers. Trees are suggested to be planted within
the Riparian Buffers, but not on the Channel Banks or Bottom. The creek restoration areas are
envisioned to contain a mix of sizes and species. Trees will be clustered to allow view corridors.
Riparian Buffer Trees:
• Acer macrophyllum (Big Leaf Maple)
• Alnus rhombifolia (White Alder)
• Arbutus menziesii (Pacific Madrone)
• Cercis occidentalis (Western Redbud)
• Quercus agrifolia (Coast Live Oak)
• Populus fremontii (Fremont Cottonwood)
• Sycamore (Platanus racemosa)
• Umbellularia californica (California Laurel)
Shrubs and Groundcover: Shrubs and groundcover are proposed to primarily be 1 gallon containers.
The creek restoration areas are envisioned to contain a mix of shrub sizes and species, with lower
growing species along the trail.
Riparian Buffer Shrubs and Groundcover:
• Artemisia douglasiana (Mugwort)
• Baccharis pilularis (Coyote Brush)
• Ceanothus species (California Wild Lilac)
• Diplacus aurantiacus (Sticky Monkeyflower)
• Garrya elliptica (Coast Silktassel)
• Heteromeles arbutifolia (Toyon)
• Muhlenbergia rigens (Deer Grass)
• Rhamnus californica (California Coffee Berry)
• Ribes speciosum (Fuchsia Flowering Gooseberry)
Channel Bank Shrubs and Groundcover:
• Asclepias fascicularis (Milkweed)
• Eleocharis acicularis (Needle Spikerush)
• Elymus glaucus (Blue Wildrye)
• Hordeum brachyantherum (California Meadow Barley)
3-6
• Leymus triticoides (Creeping Wild Rye)
• Mimulus guttatus (Seep Monkeyflower)
• Symphoricarpos mollis (Creeping Snowberry)
Channel Bottom:
• Alisma plantago-aquatica (Water Paintain)
• Cyperus eragrostis (Umbrella Sedge)
• Juncus species (Rush)
• Scirpus species (Bulrush)
3.7 Froom Creek Restoration Sections
The following conceptual sections are intended to show typical areas of creek restoration along the
realigned corridor. The sections show the general planting and grading concepts for the Riparian Buffer,
Channel Bank, and Channel Bottom zones. The sections also conceptually demonstrate the pedestrian
trail and road crossings proposed along the creek corridor.
Section A.1 to A.3: Sections A.1 through A.3 (Figure 3-3, 3-4, 3-5) are intended to represent typical cross
sections of the Froom Creek restoration, to demonstrate the proposed undulation and meandering
nature of the creek enhancements The Channel Bottom area is proposed to include a meandering low-
flow channel that will facilitate the typical drainage for the creek corridor, and the Channel Banks will
control seasonal and 100-year flooding (high water line). It is anticipated that boulders, cobbles, logs,
and embedded tree roots will be placed in key locations along the Channel Bank and Channel Bottom to
provide habitat areas.
3-7
Figure 3.3: Section A-1
3-8
Figure 3.4: Section A-2
3-9
Figure 3.5: Section A-3
3-10
Section B: Section B (see Figure 3-6) is intended to represent a typical road crossing at Froom Creek.
The Channel Bottom area is proposed to be a natural bottom, and the overhead roadway crossing
facilitated with a “Conspan” natural bottom culvert. The culvert is envisioned to be enhanced with a
railing and decorative concrete, and armored with boulders, cobble and vegetation. The upper deck of
the culvert is proposed to accommodate pedestrians, bicyclists, and vehicles.
Figure 3.6: Section B
3-11
Section C: Section C is intended to represent a typical cross section where Froom Creek is proposed
adjacent to the existing wetlands. The Channel Bottom is proposed to be configured so that the creek
overbank will flow into the adjacent existing wetlands during storm larger than 2-year events.
Figure 3.7: Section C
3.8 Conclusion
The Froom Creek Restoration program, as proposed, conforms to guidelines for creek design and
planting as outlined by the City of San Luis Obispo’s Waterway Management Plan and the California
Salmonid Stream Habitat Restoration Manual. The restored lower reach of the Froom Creek corridor will
protect and enhance creek, riparian, fish, and wetland habitats in the Froom Ranch Specific Plan area.
Appendix 1
HEC - RAS Summary Table and Cross Sections
River 2
3453.96
3210.45
2422.36
2031.65
1757.69
1429.43
912.75
603.53 218.37
HEC-RAS Plan: Plan 03 River: Main 2 Reach: River 2
Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl
(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)
River 2 4164.67 2 yr 289.20 122.85 126.65 126.62 127.50 0.015272 7.41 39.03 21.95 0.98
River 2 4164.67 10yr 394.30 122.85 127.12 127.09 128.08 0.014664 7.88 50.04 24.91 0.98
River 2 4164.67 25 yr 489.10 122.85 127.48 127.44 128.53 0.014264 8.23 59.45 27.19 0.98
River 2 4164.67 50 yr 612.20 122.85 127.89 127.85 129.04 0.013847 8.60 71.16 29.78 0.98
River 2 4164.67 100 yr 691.80 122.85 128.13 128.09 129.34 0.013661 8.82 78.39 31.28 0.98
River 2 3969.73 2 yr 289.20 120.21 124.22 123.99 124.90 0.011357 6.58 43.96 23.70 0.85
River 2 3969.73 10yr 394.30 120.21 124.63 124.45 125.46 0.012068 7.28 54.18 26.30 0.89
River 2 3969.73 25 yr 489.10 120.21 124.94 124.81 125.89 0.012634 7.82 62.56 28.25 0.93
River 2 3969.73 50 yr 612.20 120.21 125.28 125.21 126.39 0.013273 8.43 72.65 30.43 0.96
River 2 3969.73 100 yr 691.80 120.21 125.49 125.44 126.68 0.013548 8.76 79.00 31.73 0.98
River 2 3714.24 2 yr 289.20 117.12 120.76 120.76 121.56 0.016383 7.20 40.19 25.24 1.01
River 2 3714.24 10yr 394.30 117.12 121.18 121.18 122.09 0.015641 7.64 51.62 28.67 1.00
River 2 3714.24 25 yr 489.10 117.12 121.51 121.51 122.49 0.015175 7.97 61.34 31.25 1.00
River 2 3714.24 50 yr 612.20 117.12 121.88 121.88 122.95 0.014706 8.33 73.51 34.31 1.00
River 2 3714.24 100 yr 691.80 117.12 122.09 122.09 123.22 0.014458 8.53 81.13 36.10 1.00
River 2 3453.96 2 yr 435.90 115.14 118.61 118.32 119.04 0.009472 5.27 82.66 55.87 0.76
River 2 3453.96 10yr 594.40 115.14 118.98 118.66 119.48 0.009242 5.71 104.13 61.25 0.77
River 2 3453.96 25 yr 737.30 115.14 119.26 118.92 119.83 0.009190 6.05 121.88 65.36 0.78
River 2 3453.96 50 yr 922.90 115.14 119.59 119.22 120.22 0.009055 6.40 144.14 70.12 0.79
River 2 3453.96 100 yr 1042.80 115.14 119.77 119.40 120.46 0.009048 6.62 157.50 72.77 0.79
River 2 3210.45 2 yr 435.90 111.66 114.50 114.50 115.29 0.015793 7.11 61.30 39.14 1.00
River 2 3210.45 10yr 594.40 111.66 114.89 114.89 115.81 0.015309 7.72 76.99 42.40 1.01
River 2 3210.45 25 yr 737.30 111.66 115.20 115.20 116.23 0.014793 8.11 90.90 45.27 1.01
River 2 3210.45 50 yr 922.90 111.66 115.56 115.56 116.71 0.014306 8.58 107.54 47.92 1.01
River 2 3210.45 100 yr 1042.80 111.66 115.79 115.79 116.99 0.013780 8.78 118.77 49.69 1.00
River 2 2422.36 2 yr 435.90 108.51 110.50 109.46 110.53 0.000818 1.50 290.01 210.43 0.23
River 2 2422.36 10yr 594.40 108.51 110.96 109.61 111.00 0.000631 1.51 392.60 231.85 0.21
River 2 2422.36 25 yr 737.30 108.51 112.36 109.73 112.37 0.000158 0.96 770.53 320.00 0.11
River 2 2422.36 50 yr 922.90 108.51 113.00 109.87 113.02 0.000114 0.94 977.81 324.27 0.10
River 2 2422.36 100 yr 1042.80 108.51 113.43 109.96 113.45 0.000095 0.93 1117.68 327.11 0.09
River 2 2031.65 2 yr 435.90 108.00 110.26 110.29 0.000679 1.29 337.03 266.26 0.20
River 2 2031.65 10yr 594.40 108.00 110.81 110.83 0.000400 1.22 487.83 283.41 0.16
River 2 2031.65 25 yr 737.30 108.00 112.32 112.32 0.000129 0.68 1086.30 649.69 0.09
River 2 2031.65 50 yr 922.90 108.00 112.98 112.99 0.000067 0.61 1517.87 652.65 0.07
River 2 2031.65 100 yr 1042.80 108.00 113.42 113.42 0.000048 0.58 1802.99 654.59 0.06
River 2 1757.69 2 yr 435.90 106.36 110.19 110.20 0.000161 0.89 487.49 227.12 0.11
River 2 1757.69 10yr 594.40 106.36 110.75 110.77 0.000142 0.96 617.59 234.25 0.10
River 2 1757.69 25 yr 737.30 106.36 112.29 112.30 0.000076 0.72 1029.70 382.16 0.08
River 2 1757.69 50 yr 922.90 106.36 112.96 112.97 0.000058 0.72 1287.34 385.79 0.07
River 2 1757.69 100 yr 1042.80 106.36 113.40 113.41 0.000049 0.72 1457.33 388.16 0.07
River 2 1429.43 2 yr 518.70 107.48 109.68 109.96 0.007914 4.18 124.07 105.45 0.68
River 2 1429.43 10yr 707.30 107.48 110.38 110.58 0.003168 3.58 197.84 106.18 0.46
River 2 1429.43 25 yr 877.20 107.48 112.15 112.21 0.001005 1.99 440.04 239.90 0.26
River 2 1429.43 50 yr 1098.10 107.48 112.86 112.91 0.000535 1.80 609.99 240.16 0.20
River 2 1429.43 100 yr 1240.80 107.48 113.31 113.36 0.000397 1.73 719.08 240.33 0.18
River 2 912.75 2 yr 518.70 103.64 108.28 108.36 0.000864 2.34 221.26 84.93 0.26
River 2 912.75 10yr 707.30 103.64 109.76 109.82 0.000425 1.93 367.01 111.16 0.19
River 2 912.75 25 yr 877.20 103.64 111.89 111.91 0.000192 1.16 757.84 272.67 0.12
River 2 912.75 50 yr 1098.10 103.64 112.69 112.71 0.000136 1.12 983.31 287.05 0.11
River 2 912.75 100 yr 1240.80 103.64 113.18 113.20 0.000113 1.10 1124.52 289.32 0.10
River 2 603.53 2 yr 518.70 97.00 108.33 108.33 0.000006 0.38 1361.62 183.55 0.02
River 2 603.53 10yr 707.30 97.00 109.80 109.80 0.000007 0.43 1636.19 191.66 0.03
River 2 603.53 25 yr 877.20 97.00 111.89 111.90 0.000008 0.41 2152.88 313.43 0.03
River 2 603.53 50 yr 1098.10 97.00 112.70 112.70 0.000008 0.46 2405.54 315.68 0.03
River 2 603.53 100 yr 1240.80 97.00 113.19 113.19 0.000009 0.48 2560.37 317.05 0.03
River 2 463.85 2 yr 518.70 95.51 108.33 108.33 0.000001 0.14 3598.84 494.73 0.01
River 2 463.85 10yr 707.30 95.51 109.80 109.80 0.000001 0.16 4329.52 501.42 0.01
River 2 463.85 25 yr 877.20 95.51 111.89 111.89 0.000001 0.16 5433.35 551.16 0.01
River 2 463.85 50 yr 1098.10 95.51 112.70 112.70 0.000001 0.19 5877.62 554.86 0.01
River 2 463.85 100 yr 1240.80 95.51 113.19 113.19 0.000001 0.20 6149.88 557.24 0.01
River 2 218.37 2 yr 518.70 100.00 108.30 102.41 108.33 0.000100 1.36 382.20 61.83 0.10
River 2 218.37 10yr 707.30 100.00 109.76 102.86 109.79 0.000100 1.49 475.99 66.56 0.10
River 2 218.37 25 yr 877.20 100.00 111.87 103.21 111.89 0.000100 1.24 706.78 132.01 0.09
River 2 218.37 50 yr 1098.10 100.00 112.67 103.62 112.69 0.000100 1.35 812.20 132.01 0.10
River 2 218.37 100 yr 1240.80 100.00 113.15 103.88 113.18 0.000100 1.42 876.44 132.01 0.10
0 100 200 300 400 500 600 70095
100
105
110
115
120
125
130
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 463
0 100 200 300 400 50090
100
110
120
130
140
150
160
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 603
0 100 200 300 400 500100
110
120
130
140
150
160
170
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 912
0 100 200 300 400105
110
115
120
125
130
135
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
WS 100 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Crit 10yr
Ground
Bank Sta
.035
Section 1429
0 100 200 300 400 500 600106
108
110
112
114
116
118
120
122
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 1757
0 100 200 300 400 500 600 700108
110
112
114
116
118
120
122
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 2031
0 100 200 300 400 500108
110
112
114
116
118
120
122
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
WS 100 yr
EG 50 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
EG 2 yr
WS 2 yr
Crit 100 yr
Crit 50 yr
Crit 25 yr
Crit 10yr
Crit 2 yr
Ground
Bank Sta
.035
Section 2422
0 50 100 150 200 250 300110
112
114
116
118
120
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
EG 25 yr
EG 10yr
WS 100 yr
Crit 100 yr
WS 50 yr
Crit 50 yr
EG 2 yr
WS 25 yr
Crit 25 yr
WS 10yr
Crit 10yr
WS 2 yr
Crit 2 yr
Ground
Bank Sta
.035
Section 3210
0 100 200 300 400 500112
114
116
118
120
122
124
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
WS 100 yr
WS 50 yr
EG 25 yr
WS 25 yr
EG 10yr
WS 10yr
Crit 100 yr
EG 2 yr
Crit 50 yr
WS 2 yr
Crit 25 yr
Crit 10yr
Crit 2 yr
Ground
Bank Sta
.035
Section 3453
0 20 40 60 80 100 120114
116
118
120
122
124
126
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
EG 25 yr
Crit 100 yr
WS 100 yr
EG 10yr
Crit 50 yr
WS 50 yr
EG 2 yr
Crit 25 yr
WS 25 yr
Crit 10yr
WS 10yr
Crit 2 yr
WS 2 yr
Ground
Bank Sta
.035
Section 3714
0 20 40 60 80 100 120118
120
122
124
126
128
130
132
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
EG 25 yr
EG 10yr
EG 2 yr
Crit 100 yr
Crit 50 yr
Crit 25 yr
Crit 10yr
Crit 2 yr
WS 100 yr
WS 50 yr
WS 25 yr
WS 10yr
WS 2 yr
Ground
Bank Sta
.035
Section 3969
0 20 40 60 80 100 120 140 160 180124
125
126
127
128
129
130
131
132
133
Froom Overall Plan: Plan 03 6/14/2017
Station (ft)Elevation (ft)
Legend
EG 100 yr
EG 50 yr
EG 25 yr
WS 100 yr
Crit 100 yr
EG 10yr
Crit 50 yr
WS 50 yr
EG 2 yr
Crit 25 yr
WS 25 yr
WS 10yr
Crit 10yr
WS 2 yr
Crit 2 yr
Ground
Bank Sta
.035
Section 4164
Appendix 2
Existing Tributary Area
Appendix 3
Proposed Peak Flow Tabulation
Index Element Name[Pre] CN[Post] CNComments1Costco Hill69.369.3The CN is derived from the existing SLO HEC-HMS Hydrology Model2Double Box @ Hwy101--The junction elements in the HEC-HMS model do not have associated CN3Froom Creek (Lower)69.382.67Post development curve number calculated by weighted area development versus landscape4Froom Creek (Top)69.369.3The CN is derived from the existing SLO HEC-HMS Hydrology Model5Froom Creek (Upper)69.369.3The CN is derived from the existing SLO HEC-HMS Hydrology Model6Froom Development69.390Post development curve number calculated by weighted area development versus landscape7Froom Realignment--The junction elements in the HEC-HMS model do not have associated CN8Home Depot + Costco9393This curve number is a similar development to the Irish Hills development and thus equal CN9Irish Hills9393The CN is derived from the Irish Hills HEC-HMS model and report10Mid SLO Creek69.369.3The CN is derived from the existing SLO HEC-HMS Hydrology Model11Mountainbrook69.369.3The CN is derived from the existing SLO HEC-HMS Hydrology Model12SLO @ E Br ST 10177--The junction elements in the HEC-HMS model do not have associated CN13SLO @ Froom ST 11897--The junction elements in the HEC-HMS model do not have associated CN14SLO-Prefumo to E Fk--The junction elements in the HEC-HMS model do not have associated CNSummary of pre-development and post development Curve Numbers
Index Element Name[Pre] Drainage Area (ac)[Post] Drainage Area (ac)[Pre] Peak Discharge (cfs)[Post] Peak Discharge (cfs)[Pre] Time of Peak[Post] Time of Peak [Pre] Volume (ac-ft)[Post] Volume (ac-ft)CFS % Change1Costco Hill108.00108.0029.7329.7312:3512:3514.0914.090.00%2Double Box @ Hwy1011175.671175.67276.27283.1513:1012:45190.09197.642.49%3Froom Creek (Lower)150.02150.0251.3576.7812:2012:2030.1336.2549.53%4Froom Creek (Top)204.20204.2038.2838.2813:5513:5533.6933.690.00%5Froom Creek (Upper)574.00574.00163.66163.6612:2012:2065.2965.290.00%6Froom Development33.5633.5618.4729.0412:2012:2020.4522.9157.20%7Froom Realignment965.34965.34237.15272.4313:1512:25150.73155.3614.88%8Home Depot + Costco30.3630.3620.0120.0112:3512:3510.4810.480.00%9Irish Hills15.2315.2315.8615.8612:1512:159.059.050.00%10Mid SLO Creek670.02670.02221.23221.2312:2012:2078.3078.300.00%11Mountainbrook60.3160.3121.1921.1912:2012:209.569.560.00%12SLO @ E Br ST 1017735833.3335833.336875.066876.8014:2514:254139.204144.870.03%13SLO @ Froom ST 1189727356.5927356.595803.825807.9414:0514:053216.103223.650.07%14SLO-Prefumo to E Fk27356.5927356.595649.875651.6114:2514:253162.203167.870.03%Froom development hydrologic summary of modeled elements [2-yr event]
Index Element Name[Pre] Drainage Area (ac)[Post] Drainage Area (ac)[Pre] Peak Discharge (cfs)[Post] Peak Discharge (cfs)[Pre] Time of Peak[Post] Time of Peak [Pre] Volume (ac-ft)[Post] Volume (ac-ft)CFS % Change1Costco Hill108.00108.0059.0659.0612:3512:3522.1322.130.00%2Double Box @ Hwy1011175.671175.67507.92507.3313:2512:50275.28286.96-0.12%3Froom Creek (Lower)150.02150.02101.56143.3812:2012:2040.9549.9441.18%4Froom Creek (Top)204.20204.2072.1872.1813:5013:5048.0348.030.00%5Froom Creek (Upper)574.00574.00347.76347.7612:2012:20106.66106.660.00%6Froom Development33.5633.5629.7045.4912:2012:2022.8726.2953.14%7Froom Realignment965.34965.34462.10531.0113:1512:25220.88227.3214.91%8Home Depot + Costco30.3630.3631.9831.9812:3012:3013.7213.720.00%9Irish Hills15.2315.2323.6823.6812:1512:1510.6910.690.00%10Mid SLO Creek670.02670.02448.35448.3512:2012:20127.83127.830.00%11Mountainbrook60.3160.3141.6441.6412:2012:2014.0214.020.00%12SLO @ E Br ST 1017735833.3335833.3314669.3214604.6613:5013:507007.977018.09-0.44%13SLO @ Froom ST 1189727356.5927356.5912208.5512154.0513:4013:405448.905460.57-0.45%14SLO-Prefumo to E Fk27356.5927356.5911998.1711957.3813:5513:555387.575397.69-0.34%Froom development hydrologic summary of modeled elements [10-yr event]
Index Element Name[Pre] Drainage Area (ac)[Post] Drainage Area (ac)[Pre] Peak Discharge (cfs)[Post] Peak Discharge (cfs)[Pre] Time of Peak[Post] Time of Peak [Pre] Volume (ac-ft)[Post] Volume (ac-ft)CFS % Change1Costco Hill108.00108.0079.4679.4612:3512:3529.6029.600.00%2Double Box @ Hwy1011175.671175.67618.59721.5613:3512:45354.89369.2416.65%3Froom Creek (Lower)150.02150.02137.10184.2412:2012:2051.1862.1434.38%4Froom Creek (Top)204.20204.2097.9097.9013:4513:4561.4261.420.00%5Froom Creek (Upper)574.00574.00479.27479.2712:2012:20145.73145.730.00%6Froom Development33.5633.5637.6554.6412:2012:1525.1629.2145.13%7Froom Realignment965.34965.34623.27712.1613:1512:25285.96294.2114.26%8Home Depot + Costco30.3630.3638.0738.0712:3012:3016.4416.440.00%9Irish Hills15.2315.2327.4927.4912:1512:1512.0712.070.00%10Mid SLO Creek670.02670.02604.34604.3412:2012:20174.13174.130.00%11Mountainbrook60.3160.3155.6855.6812:2012:2018.1918.190.00%12SLO @ E Br ST 1017735833.3335833.3319834.1819790.5813:4513:459381.039394.05-0.22%13SLO @ Froom ST 1189727356.5927356.5916351.5816313.9113:3513:357238.207252.55-0.23%14SLO-Prefumo to E Fk27356.5927356.5916132.1816095.4413:5013:507167.097180.12-0.23%Froom development hydrologic summary of modeled elements [25-yr event]
Index Element Name[Pre] Drainage Area (ac)[Post] Drainage Area (ac)[Pre] Peak Discharge (cfs)[Post] Peak Discharge (cfs)[Pre] Time of Peak[Post] Time of Peak [Pre] Volume (ac-ft)[Post] Volume (ac-ft)CFS % Change1Costco Hill108.00108.0095.6095.6012:3512:3535.2635.260.00%2Double Box @ Hwy1011175.671175.67771.271029.2713:3012:35414.62430.7833.45%3Froom Creek (Lower)150.02150.02166.21216.8612:2012:2058.9971.1730.47%4Froom Creek (Top)204.20204.20115.11115.1113:4513:4571.4571.450.00%5Froom Creek (Upper)574.00574.00586.26586.2612:2012:20175.56175.560.00%6Froom Development33.5633.5644.1761.9312:2012:1526.9131.3340.22%7Froom Realignment965.34965.34747.75855.4013:1512:25334.75344.7514.40%8Home Depot + Costco30.3630.3642.7642.7612:3012:3018.3918.400.00%9Irish Hills15.2315.2330.7830.7812:1512:1513.0713.070.00%10Mid SLO Creek670.02670.02732.85732.8512:2012:20209.35209.350.00%11Mountainbrook60.3160.3167.2467.2412:2012:2021.3621.360.00%12SLO @ E Br ST 1017735833.3335833.3324064.0223926.3513:4013:4011409.0911424.05-0.57%13SLO @ Froom ST 1189727356.5927356.5920095.6819938.7713:3013:308833.348849.50-0.78%14SLO-Prefumo to E Fk27356.5927356.5919786.3619643.4213:4513:458750.228765.18-0.72%Froom development hydrologic summary of modeled elements [50-yr event]
Index Element Name[Pre] Drainage Area (ac)[Post] Drainage Area (ac)[Pre] Peak Discharge (cfs)[Post] Peak Discharge (cfs)[Pre] Time of Peak[Post] Time of Peak [Pre] Volume (ac-ft)[Post] Volume (ac-ft)CFS % Change1Costco Hill108.00108.00107.91107.9112:3512:3536.8236.820.00%2Double Box @ Hwy1011175.671175.67896.791230.7213:2512:30431.98448.3737.24%3Froom Creek (Lower)150.02150.02187.49243.0912:2012:2061.0973.5729.65%4Froom Creek (Top)204.20204.20128.84128.8413:4513:4574.4874.480.00%5Froom Creek (Upper)574.00574.00664.08664.0812:2012:20183.63183.630.00%6Froom Development33.5633.5648.9268.3012:2012:1527.3831.9039.60%7Froom Realignment965.34965.34840.78962.4013:1512:25349.07358.7814.47%8Home Depot + Costco30.3630.3647.5347.5312:3012:3018.9218.930.00%9Irish Hills15.2315.2334.0434.0412:1512:1513.3313.330.00%10Mid SLO Creek670.02670.02829.32829.3212:2012:20218.84218.840.00%11Mountainbrook60.3160.3175.9375.9312:2012:2022.2122.210.00%12SLO @ E Br ST 1017735833.3335833.3327724.5827523.2113:3513:3512346.6312361.76-0.73%13SLO @ Froom ST 1189727356.5927356.5923113.2522872.2313:2513:259645.169661.56-1.04%14SLO-Prefumo to E Fk27356.5927356.5922761.0122513.3713:4013:409561.669576.79-1.09%Froom development hydrologic summary of modeled elements [100-yr event]
Appendix 4
Soils Information
GeoSolutions - Soils & Geology, June, 2016
Appendix 5
FIRM Maps
Appendix 6
City of San Luis Obispo – Storm Water Control Plan Application
Stormwater Control Plan for Post Construction Requirements
Application Submittal
Where directions state “Done” that means no additional information or forms below that point needs to be
filled out or furnished.
See Exhibits for Watershed Management Zones, Basins, & Urban Sustainability Areas
Use “n/a” where information requested is not applicable. If you are unsure regarding how to fill out any of
the information, please come in and request assistance from a staff person.
Project Information
Step 1
Applicant Name: Tim Walters
Application No:
Project Name: Froom Ranch Specific Plan
Location Address: Area northwest of the intersection of Calle Joaquin and Los Osos Valley Road
Location APN: 067-241-30 & 067-241-31
Site Zoning: Residential R-3-SP, & R-4-SP, Commercial CR-SP, Parks P-F-SP and Open Space C/OS-SP
Project Type: Commercial Detached Single Family Residential
Industrial Multi-unit Residential
Mixed Use Public
Project Phase: Specific Plan
Project Description: Construction of Medium to High Density Residential, a Life Plan Community and
Commercial Retail including roads utilities and drainage facilities to serve the
project.
Total Project Site Area = 109.7 acres
Your project is NOT subject to Post Construction Requirements if…
Step 2
Area (c) of project is < 2,500 square feet – Done
OR
Area (c) of project is > 2,500 square feet, and is a project type listed below ( type) – Done
Road & parking surface repair – slurry & fog & crack seal, pothole & spot patching, overlay &
resurfacing & other damage repair with no expansion
Road & parking shoulder grading
Road & parking cleaning, repairing, maintaining, reshaping, regarding drainage systems
Sidewalk & bike path / lane project – no other impervious service created and runoff is directed to
vegetated area
Curb & gutter improvement or replacement – no other impervious created
Underground utility project – surface replaced in kind
Utility vaults – Ex: lift stations, backflows
Fuel storage – above ground with spill containment
Photovoltaic systems – on existing impervious surface, over pervious surface with vegetated cover,
buffer strip at the most down gradient row of panels
Second story – no increase in building footprint
Decks & stairs & walkways – raised with space below for drainage
Temporary structures – in place less than 6 months
Otherwise, your project is subject to the Post Construction Requirements
Stormwater Control Plan for Post Construction Requirements
Project Site Details
Step 3
Watershed Management Zone: Zone 1 & Zone 9
Urban Sustainability Area Name: N/A Meet USA Conditions
Areas
(a) Total New Impervious Surface Area = 38.7 ac
(b) Total Replaced Impervious Surface Area = 0 ac
(c) Total Existing Impervious Area = 0 ac
(d) Total Impervious Area of Completed Project = 38.7 ac
(e) Net Impervious Area: (a+b) – (c-d) =
OR where (c-d) is a negative number: (a+b) =
38.7 ac
See Area calculations in Step 3 to compare to thresholds in each Step below
Where directions state “Go To”, fill out and attach the referenced Form and any supporting documents
Step 4
Project is > 2,500 square feet
Yes - Go To Requirement 1 – Site Design & Runoff Reduction - Form 1 AND THEN
Go To Step 5
Step 5
Detached single family residential project where Area (e) is > 15,000 square feet OR
Project where Area (e) > 5,000 square feet
Yes - Go To Requirement 2 – Water Quality Treatment - Form 2 AND THEN
Go To Step 6
No - Done
Step 6
Detached single family residential project where Area (e) > 15,000 square feet OR
Project where Area (a+b) > 15,000 square feet
AND is in Watershed Management Zone 4,7,10 over a ground water basin OR in Zone 1,2,5,6,8,9
Yes - Go To Requirement 3 – Runoff Retention - Form 3 AND THEN
Go To Step 7
No - Done
Step 7
Project where Area (a+b) > 22,000 square feet AND is in Watershed Management Zone 1,2,3,6,9
Yes - Go To Requirement 4 – Peak Management - Form 4
No - Done
Exhibits
1. Watershed Management Zones
2. Groundwater Basin Location
3. Watershed Management Zone Revision Request
4. Urban Sustainability Conditions and Maps of Approved Areas
Stormwater Control Plan for Post Construction Requirements Form 1
Requirement 1 – Site Design and Runoff Reduction:
Identify the strategies used to reduce runoff through site design. Strategies 1-5 required.
Describe or attach simple plan details for 1. – 5.
1. Limit disturbance of creeks and natural drainage features and setback development from these features.
A portion of Froom Creek will be re-routed and the channel size will be increased to reduce velocity and to
accommodate 100-year storm flow rates.
2. Minimize compaction of highly permeable soils.
The site has highly impermeable soils; however a large portion of the property is to remain undeveloped
and these portions will not be compacted.
3. Minimize clearing of native vegetation and grading, conserving natural areas and maximizing undisturbed
areas, and developing along natural landforms.
Only a portion of the 109.7 acre site is to be developed. Undeveloped areas will be left undisturbed.
4. Minimize impervious surfaces including roadways and parking lots
Sidewalk and street widths will be minimized to reduced overall site imperviousness.
5. Do one of the following:
Direct roof run off into cistern, rain barrel, or vegetated area
Direct driveway and/or parking area into vegetated area
Construct surfaces (bike lanes, walks, driveways, parking areas) with permeable surfaces
Stormwater Control Plan for Post Construction Requirements Form 2
Requirement 2 – Water Quality Treatment:
(Reference Post Construction Stormwater Management Requirements for Development Projects in the Central
Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region –
for details regarding requirements – Section B.3 and Section C. Alternative Compliance.)
Treatment
Location On Site Off Site - Alternative Compliance
Measure Used 1. Harvesting, infiltration, evapotranspiration
2. Bio-filtration Treatment (Document inability to use 1.)
3. Non-Retention Based Treatment (Document inability to use 1. or 2.)
Description of structural controls:
Since soils are poorly suited for infiltration, stormwater will be conveyed to bio-retention areas. Retention areas
have been sized to hold the required water quality volume.
Alternative compliance measures:
N/A
Attachments
Attach treatment/sizing calculations, including any volume treated with off-site compliance.
Attach construction and planting details and specifications for bio-filtration options
Attach documentation regarding Treatment Measure selection
Attach infeasibility analysis where alternative compliance is proposed.
Certification
I Tim Walters certify that the systems selected and sized, as demonstrated in the attached calculations, meet
the Water Quality Treatment required for this project per the Post Construction Requirements adopted by the
Central Coast Regional Water Quality Control Board. Where identified in the attached documentation, Water
Quality Treatment will be met through alternative compliance.
Signature Date
Stormwater Control Plan for Post Construction Requirements Form 3
Requirement 3 – Runoff Retention:
(Reference Post Construction Stormwater Management Requirements for Development Projects in the Central
Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region –
for details regarding requirements – Section B.4 and Section C. Alternative Compliance.)
If a revision to the site’s Watershed Management Zone is being requested, attach Watershed Management
Revision Request Form (Exhibit) and supporting documentation.
Rainfall maps are available from the Regional Water Quality Control Board
Site Assessment Measures Summary
Attach documentation of the following information:
Site topography
Development envelope
Hydrologic features including natural areas, wetlands, watercourses, seeps, springs, and required setbacks
Vegetative cover including trees
Open space requirements
Location of groundwater wells used for drinking water
Depth to seasonal high groundwater
Soil types and hydrologic soil groups
Depth to impervious layer such as bedrock
Presence of unique geology (e.g. karst)
Geotechnical hazards
Existing structures, utilities, and drainage infrastructure including municipal storm drain system components
Existing easements and covenants
Documented soil or groundwater contamination
Source and estimated stormwater run-on from offsite, coming to project area
Drainage Management Areas (B.4.d.iii)
Drainage management strategies by Drainage Management Area
Runoff reduction measures and any structural control measures by Drainage Management Area (or full site
as appropriate)
Technical infeasibility limits on-site compliance
10% of equivalent impervious surface area is dedicated to retention based stormwater control
measures – No alternative compliance for retention
Runoff volume - compliance not achieved on-site:
Alternative compliance for retention proposed
Runoff volume – compliance not achieved onsite:
Runoff volume – alternative compliance used:
Analysis and Sizing
Attach calculated Tributary Areas and Design Volumes per the Post Construction Stormwater Management
Requirements – Attachment D
Adjustment made for redevelopment
Adjustment made for being in, and meeting requirements of, an Urban Sustainability Area
Control Mechanism
Site in Zone 1, 4, 7, and/or 10 and over groundwater basin
95th percentile event retained via infiltration
Stormwater Control Plan for Post Construction Requirements Form 3
Finding of technical infeasibility
Site in Zone 2
95th percentile event retained via storage, harvesting, infiltration, and/or evapotranspiration
Finding of technical infeasibility – Structural Stormwater Measure proposed
Site in Zone 5 and/or 8
85th percentile event retained via infiltration
Finding of technical infeasibility – Structural Stormwater Measure proposed
Site in Zone 6 and/or 9
85th percentile event retained via storage, harvesting, infiltration, and/or evapotranspiration
Finding of technical infeasibility – Structural Stormwater Measure proposed
Attachments
Attach Attachment D calculations for hydrologic analysis and stormwater control measure sizing
Attach discussion of technical infeasibility for structural stormwater measure, where proposed in lieu of
preferred storage, harvesting, infiltration, and/or evapotranspiration, include justification for any non-
retention based controls
Attach documentation of technical infeasibility for on-site compliance, including a site specific hydrologic
and/or design analysis supporting findings
Attach description of alternative compliance project including a summary description of pollutant and flow
reduction comparing the expected aggregate results of the alternate project to the results that would
otherwise have been achieved by meeting the numeric performance requirements onsite.
Attach Attachment E calculations for retention requirement adjustment for technical infeasibility
Attach Attachment F calculations for off-site retention requirements
Attach agreement for alternative compliance site use, for purposes of achieving compliance
Attach Operations and Maintenance Plan for all stormwater control measures (include any Peak
Management facilities)
Post-Construction Owner Identification
At the time of completion of the construction work, and the shift to post-construction stormwater controls, the
below listed owner is responsible for Operations and Maintenance of stormwater control measures:
Villaggio – Life Plan Community
John Madonna
(If responsibilities are divided, list all responsible owners and associated measures.)
Certification
I Tim Walters certify that the systems selected, sized, and designed as demonstrated in the attached calculations,
meet the Runoff Retention Performance Requirement for this project per the Post Construction Requirements
adopted by the Central Coast Regional Water Quality Control Board. Where identified in the attached
documentation, Runoff Retention will be met through alternative compliance.
Signature Date
Stormwater Control Plan for Post Construction Requirements Form 4
Requirement 4 – Peak Management
(Reference Post Construction Stormwater Management Requirements for Development Projects in the Central
Coast Region – Adopted July 12, 2013 California Regional Water Quality Control Board Central Coast Region –
for details regarding requirements – Section B.5)
Show any stormwater control measures used to meet the requirements of this section, in the documentation
and attachments required for Retention (Form 3), including in all mapping and Operations and Maintenance
materials.
Peak Management Compliance
Post-development peak flows, discharged from the site, do not exceed pre-project peak flows for the 2
through 10 years storm events.
Technical infeasibility limits on-site compliance
Alternative compliance for retention proposed
Runoff volume – compliance not achieved onsite:
Runoff volume – alternative compliance used:
Attachments
Attach calculations showing pre-project discharge and post-project discharge for the 2 through 10 year storm
events
Attach documentation of technical infeasibility for on-site compliance, including a site specific hydrologic
and/or design analysis supporting findings
Attach description of alternative compliance project including a summary description of pollutant and flow
reduction comparing the expected aggregate results of the alternate project to the results that would
otherwise have been achieved by meeting the numeric performance requirements onsite.
Attach agreement for alternative compliance site use, for purposes of achieving compliance
Post-Construction Owner Identification
At the time of completion of the construction work, and the shift to post-construction stormwater controls, the
below listed owner is responsible for Operations and Maintenance of the peak management control measures:
Villaggio – Life Plan Community
John Madonna
(If responsibilities are divided, list all responsible owners and associated measures.)
Certification
I Tim Walters certify that the systems selected, sized, and designed as demonstrated in the attached calculations,
meet the Peak Management requirements for this project per the Post Construction Requirements adopted by
the Central Coast Regional Water Quality Control Board. Where identified in the attached documentation, Peak
Management will be met through alternative compliance.
Signature Date
Stormwater Control Plan for Post Construction Requirements Exhibit 1
Watershed Management Zones
Stormwater Control Plan for Post Construction Requirements Exhibit 2
Ground Water Basin
Stormwater Control Plan for Post Construction Requirements Exhibit 3
Watershed Management Zone Revision Request
It is understood that Watershed Management Zones were developed through the Central Coast Regional Water
Quality Control Board Joint Effort with available data, at varying degrees of detail and accuracy. Zones may vary
across properties, or be off from verifiable, on the ground data. Applicants may propose revisions to the designate
Watershed Management Zone for the project.
Applicants should carefully review the Post-Construction Stormwater Management Requirements For
Development Projects in the Central Coast Region, California – Technical Support Document for a clear
understanding of the basis of the Watershed Management Zone designations before proceeding with this
application.
Site Information
Project Address: Area northwest of the intersection of Calle Joaquin and Los Osos Valley Road
Current Watershed Management Zone(s): Zone 1 & 9
Proposed Watershed Management Zone(s): Zone 1 & 9
Watershed Management Zone Summary
Copy table for multiple zones in the Project area
Mark the characteristics supported by geotechnical observation in the column marked ”(P)”
Identify the page number in any geotechnical report reference in the column marked “Pg”
Watershed Management Zone 1 2 3 4 5 6 7 8 9 10 (P) Pg
Drains to:
Stream
Wetland
Stream or Wetland
Lake
River
Lake or River
Underlain by:
0-10% All types
> 40% All types 4
0-40% Quaternary & Late Tertiary
10-40% Quaternary & Late Tertiary
0-10% Early to Mid-Tertiary
10-40% Early to Mid-Tertiary
10-40% Franciscan melange, Pre-Quaternary
crystalline, Early to Mid-Tertiary 5
> 40% Quaternary, Late Tertiary, Early to Mid-
Tertiary
0-10% Franciscan melange, Pre-Quaternary
crystalline
> 10% Franciscan melange, Pre-Quaternary
crystalline 2
10-40% Franciscan melange, Pre-Quaternary
crystalline 3
> 40% Franciscan melange, Pre-Quaternary
crystalline
Stormwater Control Plan for Post Construction Requirements Exhibit 3
Watershed Management Zone 1 2 3 4 5 6 7 8 9 10 (P) Pg
Slope:
Steep
Moderate
Low
Watershed Process:
Infiltration dominant 1
Infiltration less dominant
Chemical & biological remediation
Overland flow minimal
Notes:
1 – Over groundwater basin
2 – Zone 9 Wetland Draining
3 – Zone 9 Stream or Wetland Draining
4 – Zone 10 Lake Draining
5 – Zone 10 Lake or River Draining
Watershed Management Zone Revision Supporting Summary
Provide written summary of geotechnical/geological information supporting revised Watershed Management
Zone designation.
N/A
Attachment
Attach geotechnical or geological information which supports revision (include page references in table
above)
Pages 6 thru 10: GeoSolutions Soils and Geotechnical Report, June 28, 2016.
Stormwater Control Plan for Post Construction Requirements Exhibit 4
Urban Sustainability Areas
Urban Sustainability Areas (USA) encompass high density urban centers where the documented objective is to
preserve or enhance and existing pedestrian-oriented and/or public transit-oriented type of urban design
through the promotion of high density redevelopment and infill.
Requirements for USAs
The City has received approval for certain sub-areas within three land use zoning areas for USAs designation,
superimposed with minimum requirements. The Zones are Retail Commercial, Downtown Commercial, and High
Density Residential. Maps are provided at the end of this document.
Site specific requirements relating to floor areas or dwelling units, surface parking allowance, and alternative
transportation meet or exceed the current Zoning Regulation requirements. To be eligible for reductions of Post-
Construction Requirements, development and redevelopment projects must meet all the USA requirements
listed below for the Zone.
A. Retail Commercial (C-R) USA Requirements
Ratio of gross building floor area to site area minimum = 3:1
Site area building coverage minimum = 90%
Project uses < 10% of area for surface parking
Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with
connections to regional transit routes and train station
Provision of bike parking spaces = minimum 15% of auto parking requirement
Sidewalks provided on both sides of the street
B. Downtown Commercial (C-D) USA Requirements
Ratio of gross building floor area to site area minimum = 3:1
Site area building coverage maximum = 100%
Project provides no surface parking, beyond incidental uses for emergency and ADA. Exception is municipal
multi-story structures provided as park-in-lieu facilities for intense site developments
Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with
connections to regional transit routes and train station
Provision of bike parking spaces = minimum 15% of auto parking requirement
Sidewalks provided on both sides of the street
C. High-Density Residential (R-4) USA Requirements
Dwelling units per net acre (net acre - excludes right-of-way, creeks, endangered & threatened species
habitat) minimum = 24 + a low or moderate income density bonus
Site area building coverage minimum = 60%
Within 8 blocks of local transit route with at least hourly daytime service Monday through Friday, with
connections to regional transit routes and train station
Provision of bike parking spaces = minimum 10% of auto parking requirement
Sidewalks provided on both sides of the street or approved alternative connection pathways
Stormwater Control Plan for Post Construction Requirements Exhibit 4
Application of Post Construction Requirements within a USA
Post Construction Requirements will be applied in USAs as follows:
A. Performance Requirement No. 1: Site Design and Runoff Reduction
The City will apply those aspects of Site Design and Runoff Reduction that are applicable.
Site design activities may be limited by the pre-project condition and density goals.
Where complete, or nearly complete lot coverage is proposed, shifting of rainwater to vegetated areas,
or for reuse may not be applicable.
B. Performance Requirement No. 2: Water Quality Treatment
The City will apply Water Quality Treatment
Where Water Quality Treatment is demonstrated as infeasible, it will be handled per C.3.b
Site specific analysis completed and endorsed to show infeasibility per sections C.1.a & c
Off-site Project description, location within the same watershed, and scheduled completion date
identified
C. Performance Requirement No. 3: Runoff Retention
The City will apply Runoff Retention
Per B.4.b.ii, the total runoff volume to be retained from replaced impervious surfaces shall be less than,
or equivalent to, the pre-project runoff volume retained
New impervious surfaces will comply with requirements of section B.4, calculated per Attachment D,
where the tributary area is a function of new impervious only
D. Performance Requirement No. 4 – Peak Management
The City will apply Peak Management Requirements
Post-development peak flows will generally not exceed pre-project peak flows for the 2 through 10 year
storm events for redevelopment sites
Technical infeasibility will apply where density goals result in space constraints as provided for in C.1.c.v.
Per C.1.a, and no site specific hydrologic or geotechnical analysis will be required.
E. Off-Site Compliance
Where an off-site compliance proposal is included in the project submittal
Location, analysis for performance requirement compliance, and project mitigation completion
schedule for off-site compliance will be required as part of the submittal.
Off-site compliance site will be within the same watershed, unless otherwise approved by the Central
Coast Water Board EO.
Stormwater Control Plan for Post Construction Requirements Exhibit 4
Maps of Approved USAs
A. Retail Commercial (C-R)
Stormwater Control Plan for Post Construction Requirements Exhibit 4
Stormwater Control Plan for Post Construction Requirements Exhibit 4
B. Downtown Commercial (C-D)
Stormwater Control Plan for Post Construction Requirements Exhibit 4
C. High-Density Residential (R-4)
Stormwater Control Plan for Post Construction Requirements Exhibit 4
Appendix 7
Cleath-Harris Groundwater Report
Groundwater Assessment 1 9/21/2018
September 21, 2018
John Madonna
John Madonna Construction Company
P.O. Box 5310
San Luis Obispo, California 93403
Subject: Groundwater Impacts Assessment
Froom Ranch Development
San Luis Obispo, California
Dear Mr. Madonna:
Cleath-Harris Geologists (CHG) has performed an assessment of groundwater impacts
resulting from the Froom Ranch Development project, San Luis Obispo, California. The
proposed project location is presented on Figure 1. The focus of this assessment is the
improvements that are proposed on the valley floor portion of the ranch. The impacts
include impacts to the wetland area along Calle Joaquin, groundwater levels,
groundwater recharge from percolation of flows in the Froom Creek stream channel, and
subsidence from lowered groundwater levels.
The existing and proposed drainage and wells on the ranch have been reviewed along
with the proposed ground surface grade and the subsurface and surface hydrology as a
basis for this analysis. Previous reports that form the partial basis for this assessment
include the RRM Preliminary Hydraulic and Hydrologic Calculations (2017) and the
GeoSolutions 2017 Subsurface Fault Investigation and Development Setback Map.
For this assessment, the project applicant provided project preliminary plans, hydrologic
investigations, fault studies, soils reports, and various data files and information. Data
provided by the project applicant included: existing improvement and project plans and
drawings, soils reports, well information, and drainage/stream flow calculations and
environmental studies. Several test pits were dug to measure the depth to water around
the forebay/detention basins. Access was provided to the property and to the wells for
water level measurements. Well head elevations were surveyed to convert depth to water
to groundwater level elevations.
CONDUCT OF STUDY
The impact assessment involved a characterization of groundwater basin sediments and
groundwater level within the valley floor area between the Irish Hills and Los Osos
Valley Road, a review of the proposed project drainage and finished grade topography,
Figure 1
Location Map
Froom Ranch
Cleath-Harris Geologists
Wells and Borings
Cross Section Lines
Specific Plan Area
Detention Basin Drains
Wetlands
Pit with Water Level (9/20/18)
Explanation
0 250 500 750 ft
A'
B'
A
B Los
O
so
s
Va
l
ley
RoadCalle JoaquinHwy. 101Ranch
Headquarters Prefumo CreekFroom Creek
Forebay Basin
Vineyard
Church
Property
Detention Basin
Groundwater Assessment 9/21/2018 2
and an evaluation of potential impacts to the wetlands and groundwater resources
resulting from the project.
Some of the tasks included in this characterization included:
1. A review of existing drainage works on the property and along Los Osos Valley
Road and the proposed changes to the subsurface/surface drains;
2. A site reconnaissance to identify hydrologic features and facilities on the property
3. A definition of existing groundwater level elevations using water levels measured
in existing wells, and exploratory holes;
4. Plotting of the groundwater level elevations using well head survey information.
5. Estimating the range of groundwater level fluctuations during wet and dry periods
based on available groundwater level records and published literature;
6. Identifying where, and at what depth, sand and gravel aquifers are present
underlying the property based on available subsurface data;
7. Identifying areas of confined groundwater resulting in artesian flow from wells
and areas of rising water/wetland areas;
SURFACE WATER/GROUNDWATER FACILITIES
The existing water facilities on the valley floor portion of the ranch include the Froom
Creek bermed drainage channel (flowing from the canyon, along the base of the hills, to
where the creek flows between Calle Joaquin and the Vineyard Church property, and
thence toward a culvert at Highway 101); A forebay basin and detention basin with
subsurface drains receives water from the commercial property to the west of the ranch;
two water supply wells (the domestic well and the irrigation well).
Froom Creek, as it exists, has been moved to the current alignment from it’s original
stream channel orientation as was documented in the RRM Hydrology Study, Figure 1-2.
The original stream channel alignment was generally parallel to the Froom Ranch
driveway. The NRCS soil survey map has “Riverwash”/xerofluvents soils in Froom
Creek Canyon and in the vicinity of the ranch buildings, and Cropley clay soils on the
remainder of the valley portion of the property. Downstream of where the creek flows out
of the canyon (watershed area of 2 square miles), the geologic maps published by the
California Geologic Survey (Wiegers, 2011) and by Lettis and Hall (1994) show an
alluvial fan along the original stream channel alignment (GeoSolutions, 2017, Plates 3A
and 7A). Typically, alluvial fan deposits are coarse grained sands and gravels at the
mouth of a canyon. The current alignment parallels the hillside for a length of about
1,500 feet. The current channel bed is comprised of sand and gravel. Adjacent trenches
excavated for seismic studies found that below the creek channel elevation, the soils were
colluvial: a mixture of clays, sands, and gravels. The on-line NRCS soils survey map
shows that much of the current channel alignment is on Obispo weathered bedrock soils.
Groundwater Assessment 9/21/2018 3
The subsurface drains at the forebay/detention basin include perimeter drains and sub-
basin drains. The western perimeter drain and the forebay/detention basin subsurface
drains flow to a surface water discharge point that feeds to the drainageway along Los
Osos Valley Road. The southern perimeter drain discharges to a leach field that allows
the water to rise into the wetland area east of the detention basin.
The domestic well (estimated pumping rate of about 10 gallons per minute) provides
water to the ranch house and also to a construction water tank. The irrigation well
(estimated pumping rate of about 300 gallons per minute) also provides water to the
construction water tank. This water is primarily used for dust control at constructions
sites. The water production from the wells is about 10 acre-feet.
PROPOSED SURFACE WATER/GROUNDWATER FACILITIES
The proposed project includes topographic modification of the site for roads, building
pads and drainage (Figure 2). As part of this modification, the stream channel for Froom
Creek along the base of the Irish Hills would be re-aligned in part to be near to the
original channel position toward Los Osos Valley Road and then turning to an alignment
parallel to Los Osos Valley Road and thence toward the base of the hills, along the
western edge of the wetland (as shown on Figure 1-4 of the RRM Hydrology Study,
returning to the existing creek channel- a distance of about 2,500 feet. The underlying
soils along this proposed alignment are predominantly clayey.
The existing stream channel and adjacent berm would be removed as a part of the grading
for the development. The existing drainage detention basins would be removed as a part
of the grading and the flow from the Home Depot/Costco property would be drained to
the modified stream channel. Excess flow from the modified stream channel (not
contained in the wetland area) would drain to an off-site detention basin proposed on the
Vineyard Church property.
Water supply to the proposed project would be from the City of San Luis Obispo and
potentially from on-site wells and wastewater would be disposed of to the City sewer.
SITE HYDROGEOLOGY
The valley floor portion of the proposed development is underlain by alluvial deposits.
The alluvium includes fan deposits at the mouth of Froom Creek Canyon and flood plain
fine-grained sediments interbedded with stream channel sands and gravels. The depth of
the alluvium reaches 200 feet near the driveway entrance to the Froom Ranch residence.
The subsurface alluvial deposits, as defined at wells and borings (located on Figure 1),
include clayey beds to a depth ranging from 25 to 50 feet below ground surface before
Figure 2
Proposed Project Grade
Froom Ranch
Cleath-Harris Geologists
Wells and Borings
Cross Section Lines
Specific Plan Area
Wetlands
Detention Basin Drains
Proposed Stream Channel
Current Stream Channel
Pit with Water Level (9/20/18)
Explanation
0 250 500 750 ft
A'
B'
A
B Los
O
so
s
Va
l
ley
RoadCalle JoaquinHwy. 101Ranch
Headquarters Prefumo CreekFroom Creek Forebay Basin
Vineyard
Church
Property
Detention Basin
127 Contour Elevation in Feet
Groundwater Assessment 9/21/2018 4
reaching the first sand and gravel bed. The cross sections on Figures 3 and 4 include the
borehole logs for some of these test holes/wells.
Groundwater saturates much of the alluvial deposits. The shallow clay bed is an aquitard
that inhibits percolation of surface water and confines the groundwater stored within the
underlying sand and gravels.
The groundwater level within the sand and gravel beds is typically at or above the level
within the shallow saturated clays and, when this occurs, some upward leakage of
groundwater occurs. Balance Hydrologics in their Calle Joaquin Wetlands groundwater
study determined, based on salt concentration ratios, that a significant “key” source of the
water feeding the wetlands was from upward leakage of groundwater from the deep sand
and gravel deposits. Other recharge to the wetland occurs from percolation of Froom
Creek surface water within the area of the alluvial fan and in the colluvial deposits along
the western edge of the valley. Overflow from Froom Creek during high stream flow
(400 cubic foot per second) conditions occurs infrequently and “may not be sufficient to
sustain both seasonal and perennial wetlands” (Balance Hydrologics, 2004).
Historically, groundwater levels on the property have fluctuated from near surface to
about 30 feet below ground surface (CHG, 2018). The lowest level occurred when the
City was extracting groundwater during the 1987-1991 drought years and has not
occurred since then.
The groundwater level measurements at the Madonna domestic well and the Artesian
well, during this investigation found that the groundwater level depth below ground
surface was about 10 feet at the Madonna domestic well on the west and at ground
surface at the Artesian Well by Calle Joaquin on July 31, 2018. The depth to water in the
proximity of the forebay/detention basins were measured in several backhoe pits on
September 20, 2018. The depths to water in the backhoe pits around the basins were
between 3 and 6 feet and inside the basins the depths to water were 2.3 feet (forebay) and
2.6 feet (detention) below the lowest point in the basins. The levels at pits 8 and 3 are
included on Cross Section A-A’ (Figure 3).
Based on historic groundwater monitoring at the Calle Joaquin wetlands, the groundwater
level at the wetlands fluctuates seasonally 2 to 4 feet with a range of about 5 feet (from 3
feet below ground to 1+ feet above ground). Surface flow out of the wetland via
drainages and culverts occurs once the water level is above grade.
PROPOSED PROJECT GRADE
The ground surface grade for the proposed development of the valley portion of the
Froom Ranch is shown on Figure 2. Over the improved portion of the valley floor on the
80
100
120
140
0 500 1,000 1,500 2,000 2,500Elevation in Feet Above Sea LevelDistance in Feet
A’
Southeast
A
Northwest
60
Madonna
Domestic Well
Calle
Joaquin
x
x
Detention
Basins Hollingsworth
Well
Alluvium
Smith & Smith
Test Hole #1
Creek
Figure 3
Hydrogeologic Cross
Section A-A’
Froom Ranch
Cleath-Harris Geologists
Explanation
Recent Water Level
(Sounded)
Current Grade
Proposed Grade
* See Figure 1 for Cross Section Alignment
x Proposed Stream
Channel
7/31/18
Projected
Basin Drains
7/31/18
7/31/89
9/20/18 9/20/18
ClaySand &GravelClayClaySand &GravelClay
0 500 1,000 1,500 2,000Elevation in Feet Above Sea LevelDistance in Feet
B’
East
B
West
60
80
100
120
140
160
Madonna
Domestic
Los Osos
Valley Road
Froom
Creek
Alluvium
Bedrock
Smith & Smith
Test Hole #1
Irish Hills
Test Hole #1
Explanation
Current Water Level
(Sounded)
Current Grade
Proposed Grade
7/31/18
Completed Well
* See Figure 1 for Cross Section Alignment
Bedrock Surface Figure 4
Hydrogeologic
Cross Section B-B’
Froom Ranch
Cleath-Harris Geologists
7/31/2018
ClaySand &GravelClayClay
Groundwater Assessment 9/21/2018 5
property, the ground surface will generally be raised to a higher elevation for the project
(Cross Sections A-A’ and B-B’ (Figures 3 and 4).
The proposed creek alignment would be incised into the fill from the mouth of the
canyon toward Los Osos Valley Road. The proposed creek would join with the drainage
ditch along Los Osos Valley Road and follow the eastern/southeastern edge of the graded
fill slope adjacent to the wetland, where the low flow creek channel will be shallow (and
above the wetland elevation). During high flow conditions with a two year frequency
event, overbank flow would go into the wetlands. RRM hydraulic sections/calculations
drawn across the low flow/overbank flow section between the fill graded slope and the
Calle Joaquin/Marriott property bank indicate that the creek/overbank wetland area can
handle flows up to 100-year frequency flows.
IMPACT ASSESSMENT
The project impacts addressed include groundwater level impacts, changes in flow to the
wetlands, subsidence, and recharge to the groundwater.
The proposed project impacts to the groundwater level are not expected to be significant
as no significant increase in groundwater extractions are proposed. Groundwater levels
in the project area may rise if the detention basin drains are removed along with the
basins. Rising water would cause more water to flow into the wetland area.
Wetland Impact
The proposed project’s impact to the wetlands would be to increase flow into the
wetlands as the Froom Creek channel would utilize the wetlands as a part of the
drainageway for winter flows and would be expected to allow more percolation into the
alluvial fan deposits at the mouth of Froom Creek Canyon and along the longer project
creek channel length resulting in a more extended period of high water levels after the
end of the rainy season.
Subsidence Impact
Subsidence has been addressed recently by Yeh and Associates for the San Luis Obispo
Groundwater Basin Characterization Study. Historically, subsidence has been observed
when groundwater levels declined 30 feet along Los Osos Valley Road in the late 1980’s.
Some of the old well concrete pad bottoms (such as at the Madonna Artesian well) are
now above grade. Yeh and Associates mapped this area as having a moderate potential
for subsidence (Yeh and Associates, Plate 2). The clayey soils identified on the soils map
Groundwater Assessment 9/21/2018 6
and in the test hole logs indicate that there is a higher potential for
compaction/subsidence. The proposed project (with no major groundwater extractions
proposed) would not result in significantly lowered groundwater levels. If groundwater
levels decline to a depth as occurred in the 1980’s due to regional or on-site pumping,
subsidence can be expected to occur. The actual depth to water where subsidence would
start to be noticed in this area has not been determined. One example of an area where
subsidence was related to groundwater level change was in Cambria, where no significant
ground deformation occurred when groundwater levels were maintained at 20 feet or
shallower.
Groundwater Recharge Impact
Groundwater recharge to the alluvial aquifers in the wetland area is anticipated to
increase as a result of the re-alignment of the Froom Creek stream channel. The longer
reach and flatter grade of the re-aligned stream channel allows for a greater surface area
and longer duration of wetted stream channel, increasing groundwater recharge when
stream flow occurs. The re-aligned stream channel will traverse alluvial fan deposits
along the old stream channel alignment and will not be flowing over Obispo weathered
bedrock soils as occurs in the current channel alignment. The detention basin
downstream of the project area, when saturated, is anticipated to result in a higher
groundwater level than currently exists and reduce the groundwater flow gradient in the
proximity to the wetlands.
CONCLUSION
The Froom Ranch Specific Plan valley area is underlain by up to 200-feet thick alluvial
deposits comprised of shallow alluvial fan deposits near the ranch headquarters and
shallow clayey deposits elsewhere underlain by permeable sand and gravel beds. The
clayey deposits confine groundwater in these deeper sand and gravel beds but do allow
for gradual upward leakage contributing water to the wetlands. Groundwater recharge
also occurs from percolation of runoff where shallow alluvial fan deposits and stream
channel deposits are present.
During wet year winters, groundwater levels are near ground surface in the higher
topographic areas of the valley and in the lower elevation wetland area above ground
surface. Historically, the groundwater level declined more than 30 feet as a result of
regional groundwater extractions during the 1987-1991 drought and subsidence was
experienced. During the most recent drought period, groundwater levels remained within
10 feet of ground surface over most of the Froom Ranch valley area and no documented
subsidence has occurred.
Groundwater Assessment 9/21/2018 7
The proposed project will raise the ground surface on the valley floor in the buildable
area and re-align the stream channel. The higher ground surface will increase the depth
to water below grade, assuming the groundwater level elevation will be similar to the
recent groundwater level elevations. The re-aligned stream channel is anticipated to
result in some increase in recharge to the groundwater basin and increase the period of
time during the winter when standing water is present in the wetland area. Groundwater
levels are anticipated to be higher for a longer period after the rainy season due to the
flatter groundwater gradient resulting from the downstream detention basin.
Very truly yours,
CLEATH-HARRIS GEOLOGISTS
Timothy S. Cleath, Certified Hydrogeologist #81
President
Groundwater Assessment 9/21/2018 8
REFERENCES
Balance Hydrologics, Inc., 2004, Hydrologic Sufficiency for Sustaining a Separated
Wetland near Calle Joaquin, San Luis Obispo, California.
Cleath-Harris Geologists, 2018, Groundwater Flow Analysis, Recycled Water Project,
San Luis Valley Sub-Area, San Luis Obispo Valley Groundwater Basin, prepared for the
City of San Luis Obispo under contract with Water Systems Consulting.
Cleveland, George, 1980, Drought and Ground Deformation, Cambria, San Luis Obispo
County, California
GeoSolutions, Inc., 2017, Subsurface Fault Investigation and Development Setback Map,
Proposed Madonna Froom Ranch Specific Plan Area, APNs 067-241-030 and -031, San
Luis Obispo Area, San Luis Obispo County, California.
RRM Design Group, 2018, Preliminary Grading Plans, Froom Ranch Development.
RRM Design Group, 2017, Preliminary Hydrologic and Hydraulic Calculations, prepared
for the Froom Ranch Specific Plan.
RRM Design Group, 2018, Well Head Survey Information.
University of California, Davis and United States Department of Agriculture Natural
Resources Conservation District, Soil Web.
Wallace Group, 2006, Storm Water Basin Grading Plan Irish Hills Plaza 1, Drawing No.
B-1.2, 48 of 66 Sheets.
Yeh and Associates, 2017, Subsidence Evaluation, San Luis Obispo Valley Groundwater
Basin Characterization Project, San Luis Obispo County, California
Appendix 8
HEC-HMS Hydraulic Modeling Results
Project: Modified_Froom(Pre-Post) Simulation Run: Proposed-2AStart of Run: 01Jan2000, 00:00 Basin Model: Froom DevelopmentEnd of Run: 01Jan2000, 23:45 Meteorologic Model: 2-yr Size A-12 km2Compute Time:12Oct2018, 11:04:47 Control Specifications:24-hr Design, 5 minHydrologicElementDrainage Area(MI2)Peak Discharge(CFS)Time of Peak Volume(AC-FT)Costco Hill0.1687529.73301Jan2000, 12:3514.089Double Box @ Hwy1011.51794267.04501Jan2000, 12:45168.115Froom Creek (Lower)0.234476.77501Jan2000, 12:2036.251Froom Creek (Upper)0.8969163.66001Jan2000, 12:2065.289Froom Development0.0524335.43801Jan2000, 12:1526.198Froom Realignment1.18931257.31901Jan2000, 12:25124.982Home Depot + Costco0.0474320.00801Jan2000, 12:3510.482Irish Hills0.023815.85701Jan2000, 12:159.048Mid SLO Creek1.0469221.23001Jan2000, 12:2078.303Mountainbrook0.0942321.19301Jan2000, 12:209.560Pref @ C Joaquin14.70162207.51001Jan2000, 12:55998.034SLO @ E Br ST 1017755.670546850.79401Jan2000, 14:254116.095SLO @ Froom ST 1189742.425645774.61001Jan2000, 14:053194.125
Project: Modified_Froom(Pre-Post) Simulation Run: Proposed-10AStart of Run: 01Jan2000, 00:00 Basin Model: Froom DevelopmentEnd of Run: 01Jan2000, 23:45 Meteorologic Model: 10-yr Size A-12 km2Compute Time:12Oct2018, 11:04:59 Control Specifications:24-hr Design, 5 minHydrologicElementDrainage Area(MI2)Peak Discharge(CFS)Time of Peak Volume(AC-FT)Costco Hill0.1687559.05801Jan2000, 12:3522.125Double Box @ Hwy1011.51794477.75901Jan2000, 12:50243.406Froom Creek (Lower)0.2344143.38301Jan2000, 12:2049.941Froom Creek (Upper)0.8969347.76501Jan2000, 12:20106.663Froom Development0.0524351.63001Jan2000, 12:1529.777Froom Realignment1.18931499.68501Jan2000, 12:25182.814Home Depot + Costco0.0474331.98001Jan2000, 12:3013.719Irish Hills0.023823.68101Jan2000, 12:1510.690Mid SLO Creek1.0469448.35201Jan2000, 12:20127.825Mountainbrook0.0942341.63501Jan2000, 12:2014.018Pref @ C Joaquin14.70164196.32701Jan2000, 13:001676.039SLO @ E Br ST 1017755.6705414567.88601Jan2000, 13:506975.220SLO @ Froom ST 1189742.4256412112.30101Jan2000, 13:405417.020
Project: Modified_Froom(Pre-Post) Simulation Run: Proposed-25AStart of Run: 01Jan2000, 00:00 Basin Model: Froom DevelopmentEnd of Run: 01Jan2000, 23:45 Meteorologic Model: 25-yr Size A-12 km2Compute Time:12Oct2018, 11:05:20 Control Specifications:24-hr Design, 5 minHydrologicElementDrainage Area(MI2)Peak Discharge(CFS)Time of Peak Volume(AC-FT)Costco Hill0.1687579.46001Jan2000, 12:3529.602Double Box @ Hwy1011.51794613.29801Jan2000, 12:50312.503Froom Creek (Lower)0.2344184.23601Jan2000, 12:2062.137Froom Creek (Upper)0.8969479.28201Jan2000, 12:20145.731Froom Development0.0524359.72501Jan2000, 12:1532.796Froom Realignment1.18931664.45901Jan2000, 12:25236.430Home Depot + Costco0.0474338.06901Jan2000, 12:3016.441Irish Hills0.023827.48601Jan2000, 12:1512.070Mid SLO Creek1.0469604.34301Jan2000, 12:20174.126Mountainbrook0.0942355.67601Jan2000, 12:2018.185Pref @ C Joaquin14.70165398.28401Jan2000, 13:052309.797SLO @ E Br ST 1017755.6705419729.60601Jan2000, 13:459338.087SLO @ Froom ST 1189742.4256416251.35401Jan2000, 13:357195.816
Project: Modified_Froom(Pre-Post) Simulation Run: Proposed-50AStart of Run: 01Jan2000, 00:00 Basin Model: Froom DevelopmentEnd of Run: 01Jan2000, 23:45 Meteorologic Model: 50-yr Size A-12 km2Compute Time:12Oct2018, 11:06:02 Control Specifications:24-hr Design, 5 minHydrologicElementDrainage Area(MI2)Peak Discharge(CFS)Time of Peak Volume(AC-FT)Costco Hill0.1687595.59601Jan2000, 12:3535.261Double Box @ Hwy1011.51794928.17001Jan2000, 12:35364.434Froom Creek (Lower)0.2344216.86001Jan2000, 12:2071.165Froom Creek (Upper)0.8969586.27701Jan2000, 12:20175.563Froom Development0.0524366.52701Jan2000, 12:1534.976Froom Realignment1.18931797.88101Jan2000, 12:25276.997Home Depot + Costco0.0474342.76201Jan2000, 12:3018.398Irish Hills0.023830.78301Jan2000, 12:1513.066Mid SLO Creek1.0469732.85401Jan2000, 12:20209.350Mountainbrook0.0942367.24301Jan2000, 12:2021.356Pref @ C Joaquin14.70166071.15901Jan2000, 13:102789.396SLO @ E Br ST 1017755.6705423882.62601Jan2000, 13:4011358.320SLO @ Froom ST 1189742.4256419895.09401Jan2000, 13:308783.155
Project: Modified_Froom(Pre-Post) Simulation Run: Proposed-100AStart of Run: 01Jan2000, 00:00 Basin Model: Froom DevelopmentEnd of Run: 01Jan2000, 23:45 Meteorologic Model: 100-yr Size A 12 km2Compute Time:16Oct2018, 11:16:33 Control Specifications:24-hr Design, 5 minHydrologicElementDrainage Area(MI2)Peak Discharge(CFS)Time of Peak Volume(AC-FT)Costco Hill0.16875107.90701Jan2000, 12:3536.819Double Box @ Hwy1011.517941132.48201Jan2000, 12:30378.904Froom Creek (Lower)0.2344243.08801Jan2000, 12:2073.567Froom Creek (Upper)0.8969664.09601Jan2000, 12:20183.637Froom Development0.0524373.18701Jan2000, 12:1535.551Froom Realignment1.18931899.65601Jan2000, 12:25288.013Home Depot + Costco0.0474347.52501Jan2000, 12:3018.925Irish Hills0.023834.03901Jan2000, 12:1513.327Mid SLO Creek1.0469829.32301Jan2000, 12:20218.839Mountainbrook0.0942375.92601Jan2000, 12:2022.210Pref @ C Joaquin14.70166547.90401Jan2000, 13:102924.130SLO @ E Br ST 1017755.6705427469.66501Jan2000, 13:3512293.146SLO @ Froom ST 1189742.4256422823.01501Jan2000, 13:259592.088
0246810121495.5096.1496.7997.4398.0798.7199.36100.0000:0003:0006:0009:0012:0015:0018:0021:0001Jan2000050100250300350400Reservoir "Double Box @ Hwy101" Results for Run "Proposed-2A"Run:Proposed-2A Element:Double Box @ Hwy101 Result:StorageRun:Proposed-2A Element:Double Box @ Hwy101 Result:Pool ElevationRun:Proposed-2A Element:Double Box @ Hwy101 Result:OutflowRun:Proposed-2A Element:Double Box @ Hwy101 Result:Combined Inflow200150Flow (cfs)Storage (AC-FT)High Water Elevation (ft)
0510152095.0096.6798.33100.00101.6700:0003:0006:0009:0012:0015:0018:0021:0001Jan20000100200300400500600700Reservoir "Double Box @ Hwy101" Results for Run "Proposed-10A"Run:Proposed-10A Element:Double Box @ Hwy101 Result:StorageRun:Proposed-10A Element:Double Box @ Hwy101 Result:Pool ElevationRun:Proposed-10A Element:Double Box @ Hwy101 Result:OutflowRun:Proposed-10A Element:Double Box @ Hwy101 Result:Combined InflowFlow (cfs)Storage (AC-FT)High Water Elevation (ft)
0510152025303595.0096.4397.8699.29100.71102.14103.57105.0000:0003:0006:0009:0012:0015:0018:0021:0001Jan200001002003005006007008009001,000Reservoir "Double Box @ Hwy101" Results for Run "Proposed-25A"Run:Proposed-25A Element:Double Box @ Hwy101 Result:StorageRun:Proposed-25A Element:Double Box @ Hwy101 Result:Pool ElevationRun:Proposed-25A Element:Double Box @ Hwy101 Result:OutflowRun:Proposed-25A Element:Double Box @ Hwy101 Result:Combined Inflow400Flow (cfs)Storage (AC-FT)High Water Elevation (ft)
051015202530354095.0096.3897.7599.12100.50101.88103.25104.62106.0000:0003:0006:0009:0012:0015:0018:0021:0001Jan200002004006008001,0001,200Reservoir "Double Box @ Hwy101" Results for Run "Proposed-50A"Run:Proposed-50A Element:Double Box @ Hwy101 Result:StorageRun:Proposed-50A Element:Double Box @ Hwy101 Result:Pool ElevationRun:Proposed-50A Element:Double Box @ Hwy101 Result:OutflowRun:Proposed-50A Element:Double Box @ Hwy101 Result:Combined InflowFlow (cfs)Storage (AC-FT)High Water Elevation (ft)
051015202530354094.0095.5097.0098.50100.00101.50103.00104.50106.0000:0003:0006:0009:0012:0015:0018:0021:0001Jan200002004006008001,0001,2001,400Reservoir "Double Box @ Hwy101" Results for Run "Proposed-100A"Run:Proposed-100A Element:Double Box @ Hwy101 Result:StorageRun:Proposed-100A Element:Double Box @ Hwy101 Result:Pool ElevationRun:Proposed-100A Element:Double Box @ Hwy101 Result:OutflowRun:Proposed-100A Element:Double Box @ Hwy101 Result:Combined InflowFlow (cfs)Storage (AC-FT)High Water Elevation (ft)
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
0:00 36.000 11.000 95.836 0.768
0:05 35.829 16.791 96.010 0.918
0:10 35.057 18.942 96.069 1.039
0:15 35.190 20.871 96.121 1.144
0:20 35.445 22.642 96.167 1.237
0:25 35.806 24.271 96.208 1.321
0:30 36.217 25.773 96.245 1.397
0:35 36.631 27.159 96.279 1.465
0:40 37.010 28.435 96.309 1.527
0:45 37.332 29.605 96.337 1.583
0:50 37.598 30.695 96.362 1.634
0:55 37.820 31.655 96.384 1.679
1:00 38.007 32.498 96.403 1.719
1:05 38.163 33.279 96.421 1.755
1:10 38.290 33.975 96.437 1.786
1:15 38.393 34.592 96.450 1.814
1:20 38.477 35.139 96.462 1.839
1:25 38.548 35.621 96.473 1.861
1:30 38.608 36.045 96.482 1.879
1:35 38.661 36.418 96.490 1.896
1:40 38.707 36.745 96.498 1.910
1:45 38.748 37.032 96.504 1.923
1:50 38.785 37.283 96.509 1.934
1:55 38.818 37.504 96.514 1.944
2:00 38.849 37.698 96.518 1.952
2:05 38.878 37.868 96.522 1.960
2:10 38.906 38.017 96.525 1.966
2:15 38.932 38.149 96.528 1.972
2:20 38.956 38.265 96.530 1.977
2:25 38.981 38.368 96.533 1.982
2:30 39.005 38.460 96.534 1.986
2:35 39.029 38.542 96.536 1.989
2:40 39.053 38.615 96.538 1.992
2:45 39.076 38.681 96.539 1.995
2:50 39.099 38.741 96.540 1.998
2:55 39.123 38.795 96.542 2.000
3:00 39.147 38.845 96.543 2.002
3:05 39.171 38.891 96.544 2.004
3:10 39.195 38.934 96.545 2.006
3:15 39.219 38.974 96.545 2.008
3:20 39.244 39.012 96.546 2.010
3:25 39.269 39.048 96.547 2.011
3:30 39.294 39.082 96.548 2.013
3:35 39.319 39.116 96.548 2.014
Double Box Culvert Outlet and Storage [2‐year]
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
3:40 39.344 39.147 96.549 2.015
3:45 39.370 39.178 96.550 2.017
3:50 39.397 39.209 96.550 2.018
3:55 39.423 39.238 96.551 2.019
4:00 39.451 39.268 96.552 2.021
4:05 39.478 39.297 96.552 2.022
4:10 39.506 39.326 96.553 2.023
4:15 39.535 39.354 96.554 2.024
4:20 39.564 39.383 96.554 2.026
4:25 39.593 39.412 96.555 2.027
4:30 39.623 39.441 96.555 2.028
4:35 39.654 39.470 96.556 2.029
4:40 39.685 39.500 96.557 2.031
4:45 39.716 39.529 96.557 2.032
4:50 39.749 39.559 96.558 2.033
4:55 39.781 39.590 96.559 2.035
5:00 39.815 39.621 96.559 2.036
5:05 39.849 39.652 96.560 2.037
5:10 39.883 39.684 96.561 2.039
5:15 39.918 39.716 96.561 2.040
5:20 39.954 39.748 96.562 2.041
5:25 39.991 39.782 96.563 2.043
5:30 40.028 39.816 96.563 2.044
5:35 40.066 39.850 96.564 2.046
5:40 40.105 39.885 96.565 2.047
5:45 40.145 39.920 96.566 2.049
5:50 40.190 39.957 96.566 2.050
5:55 40.263 39.997 96.567 2.052
6:00 40.387 40.046 96.568 2.054
6:05 40.585 40.111 96.570 2.057
6:10 40.845 40.201 96.571 2.061
6:15 41.134 40.318 96.574 2.066
6:20 41.425 40.461 96.577 2.072
6:25 41.699 40.625 96.580 2.079
6:30 41.944 40.804 96.584 2.087
6:35 42.163 40.991 96.588 2.095
6:40 42.365 41.181 96.592 2.103
6:45 42.554 41.373 96.596 2.111
6:50 42.734 41.564 96.600 2.119
6:55 42.906 41.752 96.604 2.127
7:00 43.071 41.938 96.608 2.135
7:05 43.232 42.121 96.612 2.143
7:10 43.392 42.301 96.615 2.150
7:15 43.551 42.478 96.619 2.158
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
7:20 43.712 42.653 96.623 2.165
7:25 43.875 42.825 96.626 2.172
7:30 44.039 42.997 96.630 2.179
7:35 44.206 43.168 96.633 2.187
7:40 44.376 43.339 96.637 2.194
7:45 44.549 43.510 96.640 2.201
7:50 44.726 43.682 96.644 2.208
7:55 44.917 43.856 96.647 2.215
8:00 45.134 44.034 96.651 2.223
8:05 45.399 44.223 96.655 2.231
8:10 45.735 44.429 96.659 2.239
8:15 46.153 44.662 96.664 2.249
8:20 46.659 44.930 96.669 2.260
8:25 47.248 45.241 96.676 2.273
8:30 47.910 45.603 96.683 2.288
8:35 48.636 46.016 96.691 2.305
8:40 49.416 46.483 96.701 2.324
8:45 50.240 47.004 96.711 2.345
8:50 51.118 47.579 96.722 2.368
8:55 52.080 48.210 96.735 2.394
9:00 53.162 48.905 96.749 2.422
9:05 54.392 49.677 96.764 2.453
9:10 55.755 50.536 96.781 2.487
9:15 57.211 51.487 96.799 2.524
9:20 58.724 52.531 96.819 2.566
9:25 60.267 53.659 96.841 2.610
9:30 61.819 54.890 96.864 2.656
9:35 63.382 56.156 96.888 2.705
9:40 64.963 57.480 96.913 2.756
9:45 66.567 58.859 96.939 2.808
9:50 68.204 60.289 96.965 2.862
9:55 69.879 61.767 96.992 2.917
10:00 71.593 62.946 97.014 2.975
10:05 73.361 64.058 97.034 3.036
10:10 75.192 65.257 97.055 3.103
10:15 77.087 66.542 97.078 3.173
10:20 79.069 67.913 97.103 3.248
10:25 81.158 69.371 97.128 3.327
10:30 83.369 70.924 97.156 3.410
10:35 85.733 72.576 97.184 3.499
10:40 88.251 74.337 97.215 3.592
10:45 90.906 76.212 97.247 3.690
10:50 93.690 78.207 97.281 3.794
10:55 96.567 80.324 97.316 3.903
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
11:00 99.482 82.556 97.353 4.018
11:05 102.420 84.896 97.392 4.136
11:10 105.369 87.334 97.432 4.259
11:15 108.321 89.860 97.473 4.384
11:20 111.333 92.468 97.515 4.513
11:25 114.477 95.161 97.558 4.644
11:30 117.833 97.952 97.602 4.779
11:35 121.855 100.889 97.647 4.920
11:40 127.200 104.087 97.697 5.072
11:45 134.613 107.752 97.753 5.244
11:50 146.939 112.318 97.822 5.455
11:55 167.934 118.651 97.916 5.744
12:00 202.071 127.797 98.049 6.168
12:05 248.056 140.760 98.232 6.793
12:10 296.483 158.910 98.479 7.635
12:15 334.101 181.364 98.772 8.633
12:20 351.973 205.317 99.071 9.663
12:25 351.299 227.231 99.335 10.593
12:30 336.619 245.248 99.544 11.334
12:35 314.277 257.823 99.688 11.843
12:40 289.661 264.829 99.768 12.122
12:45 267.781 267.045 99.793 12.210
12:50 249.633 265.714 99.778 12.158
12:55 234.644 261.962 99.735 12.008
13:00 221.858 256.624 99.675 11.794
13:05 211.138 250.314 99.603 11.540
13:10 202.352 243.499 99.524 11.263
13:15 195.274 236.562 99.444 10.979
13:20 189.477 229.758 99.364 10.698
13:25 184.624 223.240 99.287 10.427
13:30 180.436 217.106 99.214 10.168
13:35 176.647 211.343 99.144 9.922
13:40 173.160 205.939 99.078 9.689
13:45 169.936 200.878 99.016 9.470
13:50 166.913 196.028 98.956 9.263
13:55 164.082 191.457 98.899 9.069
14:00 161.464 187.194 98.846 8.886
14:05 159.041 183.217 98.795 8.714
14:10 156.800 179.508 98.748 8.553
14:15 154.743 176.048 98.703 8.401
14:20 152.838 172.822 98.662 8.259
14:25 151.085 169.816 98.623 8.125
14:30 149.480 167.017 98.586 8.001
14:35 147.978 164.408 98.552 7.884
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
14:40 146.560 161.975 98.520 7.774
14:45 145.229 159.703 98.489 7.671
14:50 143.891 157.572 98.461 7.574
14:55 142.424 155.553 98.434 7.482
15:00 140.695 153.600 98.408 7.392
15:05 138.619 151.661 98.381 7.303
15:10 136.292 149.694 98.355 7.212
15:15 133.893 147.745 98.327 7.118
15:20 131.568 145.632 98.299 7.022
15:25 129.414 143.586 98.271 6.924
15:30 127.510 141.495 98.242 6.827
15:35 125.845 139.490 98.214 6.732
15:40 124.381 137.553 98.187 6.640
15:45 123.076 135.698 98.161 6.551
15:50 121.896 133.933 98.136 6.466
15:55 120.824 132.260 98.112 6.385
16:00 119.849 130.679 98.090 6.309
16:05 118.942 129.189 98.069 6.236
16:10 118.093 127.784 98.049 6.168
16:15 117.296 126.461 98.030 6.103
16:20 116.539 125.212 98.012 6.041
16:25 115.817 123.995 97.994 5.983
16:30 115.133 122.773 97.976 5.929
16:35 114.476 121.634 97.960 5.878
16:40 113.846 120.568 97.944 5.830
16:45 113.247 119.569 97.929 5.785
16:50 112.671 118.632 97.916 5.743
16:55 112.114 117.749 97.903 5.703
17:00 111.578 116.915 97.890 5.665
17:05 111.052 116.126 97.879 5.629
17:10 110.536 115.376 97.867 5.595
17:15 110.036 114.662 97.857 5.562
17:20 109.547 113.980 97.847 5.531
17:25 109.069 113.326 97.837 5.501
17:30 108.604 112.700 97.827 5.473
17:35 108.148 112.097 97.818 5.445
17:40 107.702 111.517 97.810 5.418
17:45 107.271 110.957 97.801 5.392
17:50 106.740 110.409 97.793 5.367
17:55 105.913 109.843 97.785 5.341
18:00 104.565 109.207 97.775 5.311
18:05 102.573 108.429 97.763 5.275
18:10 100.091 107.453 97.748 5.230
18:15 97.413 106.259 97.730 5.174
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
18:20 94.803 104.871 97.709 5.109
18:25 92.422 103.339 97.685 5.036
18:30 90.395 101.723 97.660 4.960
18:35 88.720 100.084 97.635 4.882
18:40 87.348 98.468 97.610 4.804
18:45 86.192 96.906 97.585 4.729
18:50 85.213 95.419 97.562 4.657
18:55 84.380 94.015 97.539 4.589
19:00 83.675 92.701 97.519 4.524
19:05 83.066 91.478 97.499 4.464
19:10 82.529 90.345 97.481 4.408
19:15 82.048 89.298 97.464 4.357
19:20 81.606 88.330 97.448 4.308
19:25 81.194 87.435 97.434 4.264
19:30 80.810 86.607 97.420 4.222
19:35 80.448 85.840 97.408 4.184
19:40 80.104 85.127 97.396 4.148
19:45 79.778 84.465 97.385 4.115
19:50 79.466 83.848 97.375 4.083
19:55 79.166 83.272 97.365 4.054
20:00 78.879 82.732 97.356 4.027
20:05 78.601 82.227 97.348 4.001
20:10 78.332 81.752 97.340 3.977
20:15 78.073 81.304 97.333 3.954
20:20 77.820 80.881 97.326 3.932
20:25 77.571 80.481 97.319 3.912
20:30 77.330 80.100 97.312 3.892
20:35 77.094 79.738 97.306 3.873
20:40 76.862 79.393 97.301 3.855
20:45 76.633 79.062 97.295 3.838
20:50 76.404 78.744 97.290 3.822
20:55 76.176 78.438 97.285 3.806
21:00 75.950 78.142 97.280 3.791
21:05 75.726 77.856 97.275 3.776
21:10 75.506 77.577 97.270 3.761
21:15 75.292 77.306 97.265 3.747
21:20 75.085 77.044 97.261 3.734
21:25 74.883 76.788 97.257 3.720
21:30 74.687 76.541 97.252 3.707
21:35 74.495 76.299 97.248 3.695
21:40 74.304 76.065 97.244 3.683
21:45 74.114 75.836 97.240 3.671
21:50 73.922 75.612 97.237 3.659
21:55 73.731 75.392 97.233 3.647
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [2‐year]
22:00 73.542 75.176 97.229 3.636
22:05 73.358 74.964 97.225 3.625
22:10 73.178 74.755 97.222 3.614
22:15 73.001 74.551 97.218 3.603
22:20 72.826 74.350 97.215 3.592
22:25 72.653 74.153 97.212 3.582
22:30 72.483 73.959 97.208 3.572
22:35 72.315 73.768 97.205 3.562
22:40 72.149 73.580 97.202 3.552
22:45 71.988 73.395 97.198 3.542
22:50 71.830 73.214 97.195 3.532
22:55 71.673 73.035 97.192 3.523
23:00 71.518 72.860 97.189 3.514
23:05 71.365 72.687 97.186 3.504
23:10 71.211 72.517 97.183 3.495
23:15 71.059 72.349 97.180 3.486
23:20 70.908 72.183 97.177 3.478
23:25 70.756 72.019 97.175 3.469
23:30 70.605 71.857 97.172 3.460
23:35 70.454 71.696 97.169 3.452
23:40 70.303 71.536 97.166 3.443
23:45 70.157 71.378 97.163 3.435
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
0:00 36.000 11.000 95.836 0.768
0:05 35.830 16.791 96.010 0.918
0:10 35.067 18.943 96.070 1.039
0:15 35.224 20.875 96.121 1.144
0:20 35.525 22.652 96.167 1.238
0:25 35.951 24.294 96.209 1.322
0:30 36.436 25.817 96.246 1.399
0:35 36.925 27.232 96.281 1.469
0:40 37.372 28.543 96.312 1.533
0:45 37.753 29.752 96.340 1.590
0:50 38.067 30.876 96.366 1.643
0:55 38.330 31.902 96.389 1.690
1:00 38.551 32.774 96.410 1.732
1:05 38.737 33.596 96.428 1.769
1:10 38.889 34.332 96.445 1.803
1:15 39.011 34.987 96.459 1.832
1:20 39.112 35.569 96.472 1.858
1:25 39.197 36.083 96.483 1.881
1:30 39.270 36.537 96.493 1.901
1:35 39.334 36.937 96.502 1.919
1:40 39.391 37.288 96.509 1.934
1:45 39.441 37.598 96.516 1.948
1:50 39.486 37.870 96.522 1.960
1:55 39.528 38.109 96.527 1.970
2:00 39.567 38.320 96.531 1.980
2:05 39.603 38.505 96.535 1.988
2:10 39.637 38.668 96.539 1.995
2:15 39.670 38.813 96.542 2.001
2:20 39.702 38.942 96.545 2.007
2:25 39.734 39.056 96.547 2.012
2:30 39.764 39.158 96.549 2.016
2:35 39.795 39.250 96.551 2.020
2:40 39.826 39.333 96.553 2.023
2:45 39.856 39.407 96.555 2.027
2:50 39.886 39.476 96.556 2.030
2:55 39.917 39.539 96.557 2.032
3:00 39.948 39.597 96.559 2.035
3:05 39.979 39.651 96.560 2.037
3:10 40.010 39.702 96.561 2.039
3:15 40.042 39.750 96.562 2.041
3:20 40.074 39.796 96.563 2.043
3:25 40.106 39.839 96.564 2.045
3:30 40.139 39.881 96.565 2.047
3:35 40.172 39.922 96.566 2.049
Double Box Culvert Outlet and Storage [10‐year]
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
3:40 40.205 39.961 96.566 2.051
3:45 40.239 40.000 96.567 2.052
3:50 40.274 40.038 96.568 2.054
3:55 40.309 40.076 96.569 2.055
4:00 40.344 40.113 96.570 2.057
4:05 40.381 40.150 96.570 2.059
4:10 40.418 40.187 96.571 2.060
4:15 40.455 40.224 96.572 2.062
4:20 40.493 40.261 96.573 2.063
4:25 40.532 40.299 96.574 2.065
4:30 40.572 40.336 96.574 2.067
4:35 40.612 40.374 96.575 2.068
4:40 40.653 40.413 96.576 2.070
4:45 40.694 40.452 96.577 2.072
4:50 40.737 40.491 96.578 2.073
4:55 40.780 40.531 96.578 2.075
5:00 40.824 40.571 96.579 2.077
5:05 40.869 40.612 96.580 2.078
5:10 40.915 40.654 96.581 2.080
5:15 40.961 40.697 96.582 2.082
5:20 41.009 40.739 96.583 2.084
5:25 41.058 40.783 96.584 2.086
5:30 41.108 40.828 96.585 2.088
5:35 41.159 40.874 96.586 2.090
5:40 41.214 40.921 96.587 2.092
5:45 41.271 40.969 96.588 2.094
5:50 41.340 41.019 96.589 2.096
5:55 41.444 41.075 96.590 2.098
6:00 41.609 41.142 96.591 2.101
6:05 41.860 41.231 96.593 2.105
6:10 42.185 41.350 96.596 2.110
6:15 42.548 41.502 96.599 2.116
6:20 42.922 41.688 96.603 2.124
6:25 43.284 41.900 96.607 2.133
6:30 43.619 42.135 96.612 2.143
6:35 43.929 42.382 96.617 2.154
6:40 44.221 42.638 96.622 2.164
6:45 44.499 42.899 96.628 2.175
6:50 44.764 43.162 96.633 2.186
6:55 45.018 43.425 96.638 2.197
7:00 45.263 43.687 96.644 2.208
7:05 45.505 43.946 96.649 2.219
7:10 45.760 44.204 96.654 2.230
7:15 46.047 44.464 96.660 2.241
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
7:20 46.394 44.734 96.665 2.252
7:25 46.827 45.023 96.671 2.264
7:30 47.359 45.341 96.678 2.277
7:35 47.991 45.702 96.685 2.292
7:40 48.720 46.113 96.693 2.308
7:45 49.532 46.582 96.703 2.328
7:50 50.416 47.110 96.713 2.349
7:55 51.360 47.701 96.725 2.373
8:00 52.353 48.354 96.738 2.400
8:05 53.392 49.067 96.752 2.428
8:10 54.473 49.838 96.767 2.459
8:15 55.590 50.665 96.783 2.492
8:20 56.746 51.546 96.800 2.527
8:25 57.939 52.479 96.818 2.564
8:30 59.169 53.463 96.837 2.602
8:35 60.438 54.523 96.857 2.642
8:40 61.749 55.598 96.877 2.684
8:45 63.100 56.723 96.899 2.727
8:50 64.575 57.901 96.921 2.772
8:55 66.345 59.162 96.944 2.819
9:00 68.613 60.558 96.970 2.872
9:05 71.518 62.167 96.999 2.932
9:10 74.978 63.466 97.023 3.004
9:15 78.774 65.037 97.051 3.091
9:20 82.725 66.891 97.084 3.192
9:25 86.673 69.011 97.122 3.308
9:30 90.511 71.367 97.163 3.434
9:35 94.243 73.922 97.208 3.570
9:40 97.898 76.646 97.254 3.713
9:45 101.517 79.513 97.303 3.862
9:50 105.135 82.509 97.353 4.015
9:55 108.769 85.619 97.404 4.173
10:00 112.432 88.834 97.456 4.334
10:05 116.173 92.149 97.510 4.497
10:10 120.012 95.565 97.564 4.664
10:15 123.959 99.083 97.619 4.834
10:20 128.066 102.708 97.676 5.006
10:25 132.369 106.452 97.733 5.183
10:30 136.890 110.330 97.792 5.363
10:35 141.692 114.361 97.852 5.549
10:40 146.774 118.564 97.915 5.740
10:45 152.108 122.957 97.979 5.937
10:50 157.686 127.255 98.041 6.142
10:55 163.434 131.644 98.104 6.356
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
11:00 169.247 136.266 98.169 6.578
11:05 175.093 141.099 98.237 6.809
11:10 180.944 146.149 98.306 7.045
11:15 186.775 151.319 98.377 7.287
11:20 192.719 156.669 98.449 7.533
11:25 198.936 162.180 98.522 7.783
11:30 205.607 167.884 98.597 8.039
11:35 213.800 173.898 98.676 8.306
11:40 224.889 180.506 98.761 8.596
11:45 240.465 188.186 98.858 8.928
11:50 266.695 197.950 98.980 9.345
11:55 310.994 211.383 99.145 9.923
12:00 382.081 231.792 99.388 10.783
12:05 476.302 262.610 99.743 12.034
12:10 573.696 303.136 100.207 13.698
12:15 647.658 351.639 100.740 15.646
12:20 680.566 396.900 101.272 17.625
12:25 676.065 420.782 101.762 19.480
12:30 643.610 439.604 102.171 21.059
12:35 595.859 457.167 102.472 22.247
12:40 543.949 471.441 102.656 22.973
12:45 497.964 477.591 102.737 23.293
12:50 459.933 477.759 102.739 23.301
12:55 428.190 473.582 102.684 23.084
13:00 401.051 466.191 102.588 22.703
13:05 378.249 456.429 102.463 22.210
13:10 359.530 446.041 102.319 21.642
13:15 344.369 439.142 102.161 21.018
13:20 331.927 431.489 101.991 20.349
13:25 321.533 422.997 101.809 19.657
13:30 312.605 414.186 101.624 18.958
13:35 304.611 405.208 101.440 18.262
13:40 297.343 396.238 101.259 17.575
13:45 290.681 383.917 101.083 16.908
13:50 284.473 368.395 100.919 16.299
13:55 278.683 354.318 100.769 15.751
14:00 273.328 341.825 100.633 15.256
14:05 268.363 330.510 100.510 14.806
14:10 263.756 320.328 100.398 14.397
14:15 259.525 311.133 100.296 14.024
14:20 255.605 302.804 100.203 13.684
14:25 252.001 295.240 100.118 13.373
14:30 248.699 288.361 100.040 13.087
14:35 245.602 282.001 99.967 12.825
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
14:40 242.678 276.094 99.899 12.585
14:45 239.934 270.697 99.836 12.364
14:50 236.982 265.747 99.778 12.159
14:55 233.299 260.879 99.723 11.965
15:00 228.287 256.120 99.669 11.774
15:05 221.630 251.217 99.613 11.576
15:10 213.805 245.971 99.553 11.364
15:15 205.594 240.319 99.487 11.133
15:20 197.658 234.331 99.418 10.888
15:25 190.412 228.141 99.345 10.631
15:30 184.193 221.927 99.272 10.371
15:35 178.969 215.859 99.199 10.115
15:40 174.576 210.028 99.128 9.865
15:45 170.801 204.501 99.061 9.627
15:50 167.524 199.305 98.997 9.402
15:55 164.666 194.310 98.935 9.190
16:00 162.167 189.698 98.877 8.993
16:05 159.934 185.453 98.824 8.811
16:10 157.917 181.548 98.774 8.641
16:15 156.091 177.958 98.728 8.485
16:20 154.407 174.657 98.685 8.340
16:25 152.828 171.615 98.646 8.205
16:30 151.330 168.806 98.609 8.080
16:35 149.882 166.201 98.575 7.964
16:40 148.488 163.778 98.543 7.855
16:45 147.176 161.517 98.514 7.753
16:50 145.949 159.405 98.485 7.657
16:55 144.800 157.432 98.459 7.568
17:00 143.722 155.587 98.434 7.483
17:05 142.689 153.858 98.411 7.404
17:10 141.696 152.234 98.389 7.329
17:15 140.746 150.707 98.368 7.259
17:20 139.828 149.266 98.349 7.192
17:25 138.932 147.903 98.330 7.128
17:30 138.052 146.647 98.313 7.068
17:35 137.167 145.377 98.296 7.010
17:40 136.280 144.208 98.279 6.954
17:45 135.407 143.095 98.264 6.901
17:50 134.412 141.936 98.248 6.848
17:55 133.072 140.825 98.233 6.796
18:00 131.128 139.645 98.216 6.740
18:05 128.443 138.315 98.198 6.676
18:10 125.210 136.770 98.176 6.603
18:15 121.787 134.993 98.151 6.517
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
18:20 118.478 133.011 98.123 6.422
18:25 115.452 130.881 98.093 6.319
18:30 112.830 128.671 98.061 6.211
18:35 110.599 126.444 98.029 6.102
18:40 108.718 124.235 97.997 5.994
18:45 107.124 121.896 97.963 5.889
18:50 105.790 119.696 97.931 5.791
18:55 104.675 117.647 97.901 5.698
19:00 103.732 115.752 97.873 5.612
19:05 102.898 114.007 97.847 5.532
19:10 102.137 112.402 97.823 5.459
19:15 101.434 110.926 97.801 5.391
19:20 100.774 109.565 97.780 5.328
19:25 100.144 108.309 97.761 5.269
19:30 99.536 107.144 97.744 5.215
19:35 98.931 106.060 97.727 5.164
19:40 98.330 105.044 97.712 5.117
19:45 97.743 104.089 97.697 5.072
19:50 97.185 103.189 97.683 5.029
19:55 96.674 102.341 97.670 4.989
20:00 96.232 101.544 97.658 4.951
20:05 95.854 100.802 97.646 4.916
20:10 95.512 100.113 97.635 4.883
20:15 95.173 99.472 97.625 4.852
20:20 94.805 98.871 97.616 4.824
20:25 94.402 98.300 97.607 4.796
20:30 93.977 97.751 97.598 4.770
20:35 93.538 97.219 97.590 4.744
20:40 93.098 96.699 97.582 4.719
20:45 92.671 96.192 97.574 4.694
20:50 92.264 95.698 97.566 4.671
20:55 91.885 95.218 97.559 4.647
21:00 91.548 94.755 97.551 4.625
21:05 91.249 94.311 97.544 4.603
21:10 90.967 93.889 97.537 4.583
21:15 90.673 93.485 97.531 4.563
21:20 90.346 93.093 97.525 4.544
21:25 89.993 92.709 97.519 4.525
21:30 89.641 92.330 97.513 4.506
21:35 89.310 91.956 97.507 4.488
21:40 89.004 91.589 97.501 4.470
21:45 88.722 91.233 97.495 4.452
21:50 88.448 90.887 97.489 4.435
21:55 88.169 90.551 97.484 4.419
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [10‐year]
22:00 87.876 90.222 97.479 4.402
22:05 87.567 89.896 97.474 4.386
22:10 87.241 89.572 97.468 4.370
22:15 86.909 89.248 97.463 4.354
22:20 86.574 88.923 97.458 4.338
22:25 86.249 88.597 97.453 4.322
22:30 85.952 88.275 97.447 4.306
22:35 85.690 87.958 97.442 4.290
22:40 85.454 87.649 97.437 4.275
22:45 85.232 87.352 97.432 4.260
22:50 85.003 87.064 97.428 4.245
22:55 84.758 86.783 97.423 4.231
23:00 84.492 86.505 97.418 4.217
23:05 84.208 86.229 97.414 4.203
23:10 83.922 85.951 97.409 4.189
23:15 83.656 85.674 97.405 4.176
23:20 83.416 85.400 97.400 4.162
23:25 83.198 85.132 97.396 4.148
23:30 82.988 84.872 97.392 4.135
23:35 82.775 84.618 97.388 4.122
23:40 82.560 84.369 97.383 4.110
23:45 82.355 84.126 97.379 4.097
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
0:00 36.000 11.000 95.836 0.768
0:05 35.832 16.792 96.010 0.918
0:10 35.085 18.944 96.070 1.039
0:15 35.287 20.881 96.121 1.145
0:20 35.674 22.671 96.168 1.239
0:25 36.221 24.337 96.210 1.325
0:30 36.844 25.899 96.248 1.403
0:35 37.471 27.368 96.284 1.475
0:40 38.044 28.744 96.317 1.542
0:45 38.532 30.026 96.347 1.603
0:50 38.934 31.209 96.374 1.659
0:55 39.270 32.296 96.399 1.710
1:00 39.554 33.289 96.421 1.755
1:05 39.791 34.187 96.441 1.796
1:10 39.985 34.996 96.459 1.833
1:15 40.141 35.720 96.475 1.865
1:20 40.270 36.365 96.489 1.894
1:25 40.379 36.937 96.502 1.919
1:30 40.472 37.443 96.513 1.941
1:35 40.553 37.890 96.522 1.961
1:40 40.625 38.285 96.531 1.978
1:45 40.689 38.633 96.538 1.993
1:50 40.746 38.939 96.545 2.006
1:55 40.800 39.210 96.550 2.018
2:00 40.849 39.448 96.556 2.028
2:05 40.894 39.659 96.560 2.038
2:10 40.938 39.845 96.564 2.046
2:15 40.980 40.010 96.567 2.053
2:20 41.020 40.157 96.571 2.059
2:25 41.060 40.288 96.573 2.065
2:30 41.098 40.406 96.576 2.070
2:35 41.137 40.512 96.578 2.074
2:40 41.176 40.608 96.580 2.078
2:45 41.214 40.696 96.582 2.082
2:50 41.252 40.776 96.584 2.085
2:55 41.291 40.850 96.585 2.089
3:00 41.330 40.919 96.587 2.092
3:05 41.369 40.983 96.588 2.094
3:10 41.408 41.044 96.589 2.097
3:15 41.448 41.101 96.590 2.099
3:20 41.488 41.156 96.591 2.102
3:25 41.529 41.209 96.593 2.104
3:30 41.570 41.260 96.594 2.106
3:35 41.611 41.310 96.595 2.108
Double Box Culvert Outlet and Storage [25‐year]
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
3:40 41.653 41.358 96.596 2.110
3:45 41.696 41.406 96.597 2.112
3:50 41.740 41.453 96.598 2.114
3:55 41.784 41.499 96.599 2.116
4:00 41.829 41.545 96.600 2.118
4:05 41.874 41.591 96.601 2.120
4:10 41.921 41.637 96.602 2.122
4:15 41.968 41.683 96.602 2.124
4:20 42.016 41.730 96.603 2.126
4:25 42.066 41.777 96.604 2.128
4:30 42.116 41.824 96.605 2.130
4:35 42.167 41.872 96.606 2.132
4:40 42.222 41.920 96.607 2.134
4:45 42.281 41.970 96.608 2.136
4:50 42.345 42.022 96.610 2.138
4:55 42.418 42.076 96.611 2.141
5:00 42.498 42.134 96.612 2.143
5:05 42.586 42.195 96.613 2.146
5:10 42.683 42.262 96.614 2.148
5:15 42.786 42.333 96.616 2.151
5:20 42.898 42.410 96.618 2.155
5:25 43.017 42.493 96.619 2.158
5:30 43.142 42.582 96.621 2.162
5:35 43.273 42.676 96.623 2.166
5:40 43.409 42.777 96.625 2.170
5:45 43.549 42.883 96.627 2.175
5:50 43.704 42.996 96.630 2.179
5:55 43.907 43.119 96.632 2.185
6:00 44.195 43.261 96.635 2.190
6:05 44.600 43.434 96.639 2.198
6:10 45.112 43.650 96.643 2.207
6:15 45.700 43.918 96.649 2.218
6:20 46.357 44.241 96.655 2.231
6:25 47.086 44.622 96.663 2.247
6:30 47.893 45.063 96.672 2.265
6:35 48.791 45.569 96.682 2.286
6:40 49.786 46.145 96.694 2.310
6:45 50.869 46.795 96.707 2.336
6:50 52.026 47.522 96.721 2.366
6:55 53.239 48.324 96.737 2.398
7:00 54.493 49.199 96.755 2.433
7:05 55.785 50.142 96.773 2.471
7:10 57.112 51.149 96.793 2.511
7:15 58.468 52.216 96.813 2.553
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
7:20 59.854 53.339 96.835 2.597
7:25 61.270 54.542 96.857 2.643
7:30 62.712 55.761 96.881 2.690
7:35 64.185 57.029 96.904 2.738
7:40 65.688 58.342 96.929 2.788
7:45 67.219 59.698 96.954 2.840
7:50 68.782 61.096 96.980 2.892
7:55 70.378 62.428 97.004 2.946
8:00 72.003 63.448 97.023 3.003
8:05 73.664 64.546 97.043 3.063
8:10 75.363 65.719 97.064 3.128
8:15 77.099 66.962 97.086 3.196
8:20 78.879 68.275 97.109 3.268
8:25 80.704 69.654 97.133 3.342
8:30 82.571 71.098 97.159 3.420
8:35 84.489 72.606 97.185 3.500
8:40 86.459 74.177 97.212 3.583
8:45 88.479 75.811 97.240 3.669
8:50 90.707 77.517 97.269 3.758
8:55 93.420 79.330 97.300 3.852
9:00 96.949 81.321 97.333 3.955
9:05 101.497 83.588 97.371 4.070
9:10 106.894 86.217 97.414 4.203
9:15 112.769 89.262 97.463 4.355
9:20 118.790 92.720 97.519 4.525
9:25 124.735 96.554 97.580 4.712
9:30 130.418 100.701 97.645 4.911
9:35 135.858 105.094 97.712 5.119
9:40 141.112 109.677 97.782 5.333
9:45 146.260 114.406 97.853 5.551
9:50 151.366 119.252 97.925 5.771
9:55 156.461 124.196 97.997 5.992
10:00 161.567 128.772 98.063 6.216
10:05 166.760 133.455 98.129 6.443
10:10 172.067 138.265 98.197 6.674
10:15 177.499 143.248 98.266 6.908
10:20 183.151 148.279 98.335 7.146
10:25 189.084 153.514 98.406 7.388
10:30 195.354 158.927 98.479 7.636
10:35 202.064 164.551 98.554 7.890
10:40 209.188 170.421 98.631 8.152
10:45 216.654 176.561 98.710 8.423
10:50 224.422 182.985 98.792 8.704
10:55 232.357 189.690 98.877 8.993
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
11:00 240.285 196.654 98.964 9.290
11:05 248.165 203.698 99.051 9.592
11:10 255.970 210.848 99.138 9.901
11:15 263.688 218.160 99.227 10.212
11:20 271.504 225.623 99.316 10.527
11:25 279.624 233.267 99.405 10.844
11:30 288.270 241.108 99.497 11.166
11:35 298.867 249.301 99.591 11.499
11:40 313.161 258.210 99.693 11.858
11:45 333.179 268.397 99.809 12.269
11:50 367.352 281.098 99.956 12.789
11:55 425.415 298.812 100.158 13.520
12:00 518.759 325.845 100.459 14.619
12:05 642.081 366.591 100.900 16.229
12:10 768.429 407.018 101.477 18.400
12:15 862.687 440.012 102.181 21.096
12:20 902.095 490.475 102.910 23.976
12:25 892.225 535.542 103.552 26.617
12:30 845.862 569.530 104.073 28.793
12:35 779.856 592.167 104.438 30.390
12:40 709.369 605.939 104.667 31.392
12:45 647.672 612.396 104.776 31.869
12:50 597.516 613.298 104.792 31.936
12:55 556.174 610.068 104.737 31.696
13:00 521.278 603.698 104.629 31.227
13:05 492.196 594.936 104.484 30.589
13:10 468.453 584.419 104.311 29.836
13:15 449.201 572.682 104.123 29.012
13:20 433.306 559.895 103.922 28.151
13:25 419.905 546.208 103.712 27.280
13:30 408.242 532.311 103.504 26.419
13:35 397.631 518.364 103.301 25.576
13:40 387.852 504.473 103.103 24.759
13:45 378.810 490.425 102.909 23.973
13:50 370.357 476.295 102.720 23.225
13:55 362.483 462.519 102.540 22.516
14:00 355.229 449.250 102.371 21.848
14:05 348.536 441.230 102.208 21.205
14:10 342.334 434.053 102.048 20.570
14:15 336.625 426.554 101.884 19.945
14:20 331.319 418.941 101.723 19.333
14:25 326.432 411.385 101.566 18.739
14:30 321.959 403.963 101.414 18.165
14:35 317.774 396.704 101.268 17.611
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
14:40 313.833 388.304 101.129 17.082
14:45 310.128 376.136 101.001 16.599
14:50 306.143 365.031 100.883 16.169
14:55 301.212 355.073 100.777 15.780
15:00 294.581 345.937 100.678 15.418
15:05 285.868 337.018 100.581 15.065
15:10 275.712 328.081 100.483 14.709
15:15 265.123 318.985 100.383 14.343
15:20 254.925 309.759 100.281 13.968
15:25 245.621 300.524 100.177 13.591
15:30 237.607 291.446 100.075 13.216
15:35 230.830 282.665 99.974 12.852
15:40 225.072 274.133 99.876 12.505
15:45 220.086 266.202 99.783 12.177
15:50 215.740 258.530 99.696 11.871
15:55 211.956 251.490 99.616 11.587
16:00 208.673 245.043 99.542 11.326
16:05 205.768 239.157 99.474 11.086
16:10 203.155 233.793 99.412 10.865
16:15 200.766 228.902 99.354 10.663
16:20 198.525 224.382 99.302 10.477
16:25 196.403 220.363 99.253 10.305
16:30 194.398 216.611 99.208 10.146
16:35 192.488 213.146 99.166 9.999
16:40 190.678 209.934 99.127 9.861
16:45 188.987 206.955 99.091 9.733
16:50 187.393 204.184 99.057 9.614
16:55 185.876 201.604 99.025 9.502
17:00 184.419 199.182 98.995 9.397
17:05 182.988 196.849 98.966 9.298
17:10 181.581 194.662 98.939 9.205
17:15 180.213 192.602 98.914 9.118
17:20 178.882 190.655 98.889 9.034
17:25 177.605 188.809 98.866 8.955
17:30 176.409 187.059 98.844 8.880
17:35 175.276 185.400 98.823 8.808
17:40 174.178 183.826 98.803 8.740
17:45 173.084 182.327 98.784 8.675
17:50 171.760 180.873 98.765 8.612
17:55 169.897 179.403 98.747 8.548
18:00 167.151 177.815 98.726 8.478
18:05 163.356 175.987 98.703 8.398
18:10 158.802 173.825 98.675 8.303
18:15 153.991 171.308 98.642 8.192
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
18:20 149.336 168.485 98.605 8.066
18:25 145.080 165.443 98.565 7.930
18:30 141.406 162.288 98.524 7.788
18:35 138.306 159.119 98.482 7.644
18:40 135.705 156.014 98.440 7.503
18:45 133.493 153.025 98.400 7.366
18:50 131.615 150.185 98.361 7.234
18:55 130.020 147.575 98.325 7.110
19:00 128.658 145.014 98.291 6.993
19:05 127.460 142.755 98.259 6.884
19:10 126.393 140.554 98.229 6.783
19:15 125.438 138.577 98.201 6.689
19:20 124.574 136.752 98.176 6.602
19:25 123.777 135.067 98.152 6.521
19:30 123.031 133.511 98.130 6.446
19:35 122.301 132.069 98.110 6.376
19:40 121.573 130.726 98.091 6.311
19:45 120.839 129.468 98.073 6.250
19:50 120.099 128.282 98.056 6.192
19:55 119.365 127.159 98.040 6.137
20:00 118.665 126.091 98.024 6.084
20:05 118.005 125.078 98.010 6.035
20:10 117.391 124.084 97.995 5.987
20:15 116.826 123.084 97.981 5.943
20:20 116.299 122.150 97.967 5.901
20:25 115.804 121.279 97.954 5.862
20:30 115.335 120.465 97.942 5.825
20:35 114.877 119.703 97.931 5.791
20:40 114.413 118.986 97.921 5.759
20:45 113.928 118.303 97.911 5.728
20:50 113.408 117.648 97.901 5.698
20:55 112.862 117.010 97.892 5.669
21:00 112.309 116.386 97.882 5.641
21:05 111.763 115.774 97.873 5.613
21:10 111.233 115.173 97.864 5.586
21:15 110.730 114.585 97.856 5.559
21:20 110.258 114.012 97.847 5.533
21:25 109.826 113.457 97.839 5.507
21:30 109.444 112.923 97.831 5.483
21:35 109.108 112.415 97.823 5.459
21:40 108.793 111.932 97.816 5.437
21:45 108.467 111.473 97.809 5.416
21:50 108.099 111.030 97.802 5.396
21:55 107.687 110.594 97.796 5.375
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [25‐year]
22:00 107.243 110.161 97.789 5.355
22:05 106.781 109.725 97.783 5.335
22:10 106.314 109.286 97.776 5.315
22:15 105.859 108.844 97.769 5.294
22:20 105.423 108.402 97.763 5.274
22:25 105.017 107.964 97.756 5.253
22:30 104.654 107.534 97.750 5.233
22:35 104.331 107.116 97.743 5.214
22:40 104.025 106.713 97.737 5.195
22:45 103.705 106.322 97.731 5.177
22:50 103.347 105.940 97.725 5.159
22:55 102.964 105.559 97.719 5.141
23:00 102.581 105.178 97.714 5.123
23:05 102.221 104.799 97.708 5.105
23:10 101.888 104.425 97.702 5.088
23:15 101.581 104.059 97.696 5.070
23:20 101.281 103.702 97.691 5.053
23:25 100.976 103.352 97.686 5.037
23:30 100.658 103.008 97.680 5.021
23:35 100.327 102.667 97.675 5.005
23:40 100.000 102.328 97.670 4.988
23:45 99.700 101.993 97.665 4.973
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
0:00 36.000 11.000 95.836 0.768
0:05 35.835 16.792 96.010 0.918
0:10 35.109 18.946 96.070 1.040
0:15 35.367 20.889 96.121 1.145
0:20 35.861 22.695 96.168 1.240
0:25 36.560 24.392 96.211 1.327
0:30 37.357 26.003 96.251 1.408
0:35 38.157 27.538 96.288 1.484
0:40 38.888 28.997 96.323 1.554
0:45 39.509 30.372 96.355 1.620
0:50 40.021 31.681 96.384 1.680
0:55 40.448 32.843 96.411 1.735
1:00 40.808 33.936 96.436 1.785
1:05 41.109 34.931 96.458 1.830
1:10 41.354 35.831 96.478 1.870
1:15 41.551 36.640 96.495 1.906
1:20 41.713 37.363 96.511 1.938
1:25 41.850 38.007 96.525 1.966
1:30 41.966 38.578 96.537 1.991
1:35 42.067 39.084 96.548 2.013
1:40 42.157 39.531 96.557 2.032
1:45 42.236 39.926 96.566 2.049
1:50 42.307 40.274 96.573 2.064
1:55 42.372 40.582 96.579 2.077
2:00 42.432 40.854 96.585 2.089
2:05 42.488 41.094 96.590 2.099
2:10 42.541 41.307 96.595 2.108
2:15 42.592 41.496 96.599 2.116
2:20 42.641 41.664 96.602 2.123
2:25 42.688 41.814 96.605 2.130
2:30 42.735 41.950 96.608 2.135
2:35 42.782 42.072 96.611 2.140
2:40 42.828 42.182 96.613 2.145
2:45 42.874 42.283 96.615 2.149
2:50 42.920 42.376 96.617 2.153
2:55 42.966 42.462 96.619 2.157
3:00 43.013 42.541 96.620 2.160
3:05 43.059 42.616 96.622 2.163
3:10 43.107 42.687 96.623 2.166
3:15 43.154 42.754 96.625 2.169
3:20 43.202 42.818 96.626 2.172
3:25 43.251 42.880 96.627 2.174
3:30 43.299 42.940 96.629 2.177
3:35 43.349 42.999 96.630 2.179
Double Box Culvert Outlet and Storage [50‐year]
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
3:40 43.399 43.056 96.631 2.182
3:45 43.451 43.112 96.632 2.184
3:50 43.507 43.168 96.633 2.187
3:55 43.568 43.224 96.634 2.189
4:00 43.636 43.281 96.636 2.191
4:05 43.713 43.341 96.637 2.194
4:10 43.800 43.404 96.638 2.196
4:15 43.898 43.472 96.639 2.199
4:20 44.006 43.545 96.641 2.202
4:25 44.124 43.625 96.643 2.206
4:30 44.251 43.711 96.644 2.209
4:35 44.388 43.803 96.646 2.213
4:40 44.532 43.904 96.648 2.217
4:45 44.683 44.011 96.651 2.222
4:50 44.840 44.126 96.653 2.227
4:55 45.004 44.248 96.655 2.232
5:00 45.171 44.376 96.658 2.237
5:05 45.343 44.511 96.661 2.243
5:10 45.521 44.653 96.664 2.248
5:15 45.712 44.801 96.667 2.254
5:20 45.931 44.958 96.670 2.261
5:25 46.202 45.129 96.673 2.268
5:30 46.549 45.321 96.677 2.276
5:35 46.989 45.545 96.682 2.285
5:40 47.526 45.809 96.687 2.296
5:45 48.153 46.124 96.693 2.309
5:50 48.894 46.497 96.701 2.324
5:55 49.819 46.942 96.710 2.342
6:00 51.018 47.486 96.721 2.364
6:05 52.563 48.161 96.734 2.392
6:10 54.418 49.001 96.751 2.426
6:15 56.486 50.024 96.771 2.466
6:20 58.665 51.230 96.794 2.514
6:25 60.878 52.604 96.821 2.568
6:30 63.062 54.123 96.850 2.628
6:35 65.207 55.789 96.881 2.691
6:40 67.318 57.518 96.914 2.757
6:45 69.405 59.325 96.947 2.826
6:50 71.474 61.195 96.982 2.896
6:55 73.524 62.824 97.011 2.968
7:00 75.560 64.192 97.036 3.044
7:05 77.594 65.647 97.062 3.124
7:10 79.636 67.182 97.090 3.208
7:15 81.683 68.789 97.118 3.295
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
7:20 83.744 70.461 97.147 3.386
7:25 85.821 72.195 97.178 3.478
7:30 87.913 73.983 97.209 3.573
7:35 90.029 75.825 97.240 3.670
7:40 92.169 77.716 97.272 3.769
7:45 94.333 79.655 97.305 3.869
7:50 96.527 81.638 97.338 3.971
7:55 98.755 83.666 97.372 4.074
8:00 101.015 85.736 97.406 4.179
8:05 103.316 87.850 97.440 4.285
8:10 105.661 90.006 97.475 4.392
8:15 108.046 92.206 97.511 4.500
8:20 110.483 94.450 97.546 4.610
8:25 112.972 96.740 97.583 4.721
8:30 115.510 99.077 97.619 4.833
8:35 118.110 101.463 97.656 4.947
8:40 120.773 103.899 97.694 5.063
8:45 123.496 106.389 97.732 5.180
8:50 126.370 108.939 97.771 5.299
8:55 129.529 111.572 97.811 5.421
9:00 133.125 114.329 97.852 5.547
9:05 137.259 117.263 97.895 5.681
9:10 141.834 120.422 97.942 5.823
9:15 146.658 123.828 97.991 5.976
9:20 151.587 127.189 98.040 6.138
9:25 156.514 130.729 98.091 6.311
9:30 161.347 134.477 98.144 6.492
9:35 166.117 138.400 98.199 6.680
9:40 170.858 142.530 98.256 6.873
9:45 175.606 146.704 98.313 7.070
9:50 180.421 150.983 98.372 7.271
9:55 185.320 155.422 98.432 7.476
10:00 190.310 159.970 98.493 7.683
10:05 195.459 164.635 98.555 7.894
10:10 200.786 169.422 98.618 8.108
10:15 206.292 174.343 98.681 8.326
10:20 212.052 179.412 98.747 8.548
10:25 218.082 184.647 98.813 8.776
10:30 224.375 190.067 98.882 9.009
10:35 231.018 195.692 98.952 9.249
10:40 238.020 201.484 99.024 9.496
10:45 245.362 207.411 99.096 9.753
10:50 253.070 213.627 99.172 10.019
10:55 261.034 220.140 99.250 10.296
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
11:00 269.089 226.954 99.331 10.582
11:05 277.190 234.043 99.414 10.876
11:10 285.281 241.349 99.499 11.175
11:15 293.302 248.835 99.586 11.480
11:20 301.619 256.476 99.673 11.788
11:25 310.699 264.353 99.762 12.103
11:30 321.078 272.330 99.855 12.431
11:35 334.739 280.982 99.955 12.784
11:40 353.749 290.744 100.066 13.185
11:45 380.423 302.456 100.199 13.670
11:50 424.894 318.057 100.373 14.305
11:55 498.518 340.797 100.622 15.215
12:00 614.535 375.613 100.995 16.578
12:05 765.898 409.759 101.533 18.613
12:10 919.755 444.181 102.276 21.472
12:15 1033.733 507.211 103.142 24.919
12:20 1080.486 565.261 104.006 28.499
12:25 1067.042 611.951 104.769 31.836
12:30 1008.735 804.741 105.316 34.299
12:35 925.650 928.170 105.453 34.929
12:40 836.445 888.918 105.412 34.740
12:45 757.323 815.495 105.329 34.359
12:50 691.917 748.178 105.243 33.964
12:55 637.159 692.405 105.159 33.580
13:00 590.607 648.293 105.075 33.192
13:05 551.678 624.047 104.976 32.744
13:10 519.830 616.325 104.843 32.162
13:15 493.942 606.624 104.679 31.442
13:20 472.645 595.510 104.493 30.631
13:25 454.908 583.417 104.295 29.765
13:30 439.840 570.678 104.091 28.873
13:35 426.618 557.122 103.879 27.973
13:40 414.849 543.046 103.664 27.082
13:45 404.238 528.925 103.454 26.212
13:50 394.455 514.868 103.250 25.368
13:55 385.387 500.962 103.054 24.556
14:00 377.007 486.823 102.861 23.780
14:05 369.233 472.857 102.675 23.046
14:10 362.001 459.322 102.500 22.355
14:15 355.336 446.752 102.335 21.705
14:20 349.130 439.810 102.176 21.078
14:25 343.386 432.762 102.019 20.458
14:30 338.073 425.380 101.859 19.849
14:35 333.055 417.970 101.703 19.256
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
14:40 328.317 410.629 101.551 18.680
14:45 323.901 403.422 101.403 18.123
14:50 319.579 396.363 101.261 17.585
14:55 315.066 387.981 101.125 17.069
15:00 310.049 375.951 100.999 16.591
15:05 304.310 364.718 100.880 16.156
15:10 298.071 354.412 100.770 15.754
15:15 291.712 344.903 100.667 15.377
15:20 285.538 335.902 100.569 15.021
15:25 279.781 327.446 100.476 14.683
15:30 274.650 319.523 100.389 14.364
15:35 270.128 312.138 100.307 14.065
15:40 266.125 305.284 100.231 13.786
15:45 262.556 298.945 100.160 13.526
15:50 259.331 293.096 100.093 13.284
15:55 256.385 287.705 100.032 13.060
16:00 253.662 282.664 99.974 12.852
16:05 251.076 277.931 99.920 12.660
16:10 248.601 273.562 99.869 12.481
16:15 246.236 269.513 99.822 12.315
16:20 243.957 265.773 99.778 12.160
16:25 241.771 262.128 99.737 12.015
16:30 239.705 258.736 99.699 11.879
16:35 237.738 255.574 99.663 11.752
16:40 235.862 252.620 99.629 11.633
16:45 234.077 249.851 99.597 11.521
16:50 232.354 247.245 99.567 11.415
16:55 230.681 244.787 99.539 11.316
17:00 229.059 242.461 99.512 11.221
17:05 227.467 240.253 99.487 11.131
17:10 225.916 238.149 99.462 11.045
17:15 224.428 236.142 99.439 10.962
17:20 222.986 234.222 99.417 10.883
17:25 221.578 232.383 99.395 10.807
17:30 220.196 230.617 99.374 10.734
17:35 218.821 228.913 99.354 10.663
17:40 217.470 227.266 99.335 10.595
17:45 216.176 225.671 99.316 10.528
17:50 214.640 224.092 99.298 10.463
17:55 212.384 222.506 99.279 10.396
18:00 208.851 220.711 99.257 10.320
18:05 203.742 218.541 99.231 10.228
18:10 197.468 215.849 99.199 10.114
18:15 190.737 212.600 99.160 9.976
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
18:20 184.174 208.859 99.114 9.815
18:25 178.179 204.765 99.064 9.639
18:30 173.076 200.482 99.011 9.453
18:35 168.870 196.064 98.957 9.265
18:40 165.403 191.733 98.903 9.080
18:45 162.460 187.599 98.851 8.903
18:50 159.928 183.698 98.801 8.735
18:55 157.753 180.050 98.755 8.576
19:00 155.901 176.661 98.711 8.428
19:05 154.313 173.534 98.671 8.290
19:10 152.937 170.661 98.634 8.163
19:15 151.732 168.030 98.599 8.046
19:20 150.640 165.623 98.568 7.938
19:25 149.627 163.419 98.539 7.839
19:30 148.670 161.396 98.512 7.748
19:35 147.742 159.533 98.487 7.663
19:40 146.837 157.810 98.464 7.585
19:45 145.958 156.210 98.443 7.512
19:50 145.099 154.717 98.423 7.443
19:55 144.272 153.318 98.404 7.379
20:00 143.495 152.006 98.386 7.319
20:05 142.767 150.776 98.369 7.262
20:10 142.077 149.620 98.354 7.208
20:15 141.411 148.533 98.339 7.158
20:20 140.747 147.567 98.325 7.110
20:25 140.087 146.560 98.311 7.064
20:30 139.445 145.605 98.299 7.020
20:35 138.819 144.716 98.286 6.979
20:40 138.204 143.888 98.275 6.939
20:45 137.593 143.091 98.263 6.901
20:50 136.971 142.319 98.253 6.863
20:55 136.342 141.486 98.242 6.827
21:00 135.722 140.747 98.232 6.792
21:05 135.114 140.026 98.222 6.758
21:10 134.512 139.322 98.212 6.724
21:15 133.910 138.633 98.202 6.691
21:20 133.302 137.956 98.193 6.659
21:25 132.707 137.290 98.183 6.627
21:30 132.154 136.637 98.174 6.596
21:35 131.655 136.003 98.165 6.566
21:40 131.193 135.390 98.157 6.536
21:45 130.745 134.799 98.148 6.508
21:50 130.278 134.227 98.140 6.480
21:55 129.787 133.667 98.132 6.453
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [50‐year]
22:00 129.279 133.117 98.125 6.427
22:05 128.763 132.572 98.117 6.401
22:10 128.253 132.032 98.109 6.374
22:15 127.763 131.498 98.102 6.349
22:20 127.291 130.972 98.094 6.323
22:25 126.834 130.455 98.087 6.298
22:30 126.390 129.947 98.080 6.273
22:35 125.954 129.449 98.072 6.249
22:40 125.523 128.959 98.065 6.225
22:45 125.100 128.479 98.059 6.201
22:50 124.681 128.007 98.052 6.178
22:55 124.263 127.542 98.045 6.156
23:00 123.850 127.085 98.039 6.133
23:05 123.437 126.634 98.032 6.111
23:10 123.023 126.188 98.026 6.089
23:15 122.614 125.747 98.019 6.067
23:20 122.203 125.310 98.013 6.046
23:25 121.792 124.878 98.007 6.025
23:30 121.383 124.449 98.000 6.003
23:35 120.973 123.982 97.994 5.983
23:40 120.561 123.521 97.987 5.962
23:45 120.152 123.067 97.980 5.942
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
0:00 36.000 11.000 95.836 0.768
0:05 35.834 16.792 96.010 0.918
0:10 35.100 18.945 96.070 1.040
0:15 35.338 20.886 96.121 1.145
0:20 35.792 22.686 96.168 1.240
0:25 36.434 24.372 96.210 1.326
0:30 37.167 25.965 96.250 1.406
0:35 37.903 27.475 96.286 1.481
0:40 38.576 28.903 96.320 1.550
0:45 39.149 30.244 96.352 1.614
0:50 39.620 31.507 96.380 1.672
0:55 40.015 32.642 96.407 1.726
1:00 40.347 33.697 96.430 1.774
1:05 40.626 34.657 96.452 1.817
1:10 40.853 35.524 96.471 1.856
1:15 41.036 36.302 96.488 1.891
1:20 41.187 36.997 96.503 1.922
1:25 41.314 37.615 96.516 1.949
1:30 41.423 38.163 96.528 1.973
1:35 41.519 38.648 96.538 1.994
1:40 41.603 39.076 96.548 2.012
1:45 41.678 39.455 96.556 2.029
1:50 41.745 39.789 96.563 2.043
1:55 41.808 40.083 96.569 2.056
2:00 41.865 40.344 96.574 2.067
2:05 41.919 40.575 96.579 2.077
2:10 41.971 40.779 96.584 2.086
2:15 42.020 40.961 96.587 2.093
2:20 42.067 41.123 96.591 2.100
2:25 42.113 41.268 96.594 2.106
2:30 42.159 41.398 96.597 2.112
2:35 42.204 41.516 96.599 2.117
2:40 42.250 41.622 96.601 2.121
2:45 42.295 41.720 96.603 2.126
2:50 42.340 41.810 96.605 2.129
2:55 42.385 41.893 96.607 2.133
3:00 42.431 41.970 96.608 2.136
3:05 42.476 42.043 96.610 2.139
3:10 42.523 42.112 96.611 2.142
3:15 42.569 42.178 96.613 2.145
3:20 42.617 42.240 96.614 2.148
3:25 42.665 42.301 96.615 2.150
3:30 42.713 42.359 96.617 2.153
3:35 42.761 42.416 96.618 2.155
Double Box Culvert Outlet and Storage [100‐year]
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
3:40 42.811 42.473 96.619 2.157
3:45 42.861 42.528 96.620 2.160
3:50 42.913 42.582 96.621 2.162
3:55 42.965 42.636 96.622 2.164
4:00 43.018 42.690 96.623 2.166
4:05 43.075 42.744 96.624 2.169
4:10 43.136 42.799 96.626 2.171
4:15 43.204 42.855 96.627 2.173
4:20 43.282 42.914 96.628 2.176
4:25 43.370 42.977 96.629 2.179
4:30 43.467 43.043 96.631 2.181
4:35 43.574 43.116 96.632 2.184
4:40 43.690 43.194 96.634 2.188
4:45 43.815 43.279 96.635 2.191
4:50 43.947 43.370 96.637 2.195
4:55 44.086 43.469 96.639 2.199
5:00 44.232 43.574 96.642 2.204
5:05 44.385 43.686 96.644 2.208
5:10 44.544 43.805 96.646 2.213
5:15 44.708 43.930 96.649 2.218
5:20 44.876 44.062 96.652 2.224
5:25 45.049 44.200 96.654 2.230
5:30 45.228 44.344 96.657 2.236
5:35 45.422 44.495 96.660 2.242
5:40 45.650 44.654 96.664 2.248
5:45 45.933 44.829 96.667 2.256
5:50 46.314 45.028 96.671 2.264
5:55 46.866 45.269 96.676 2.274
6:00 47.662 45.577 96.682 2.286
6:05 48.757 45.984 96.691 2.303
6:10 50.127 46.521 96.701 2.325
6:15 51.697 47.206 96.715 2.353
6:20 53.393 48.043 96.732 2.387
6:25 55.152 49.024 96.751 2.426
6:30 56.924 50.137 96.773 2.471
6:35 58.699 51.363 96.797 2.520
6:40 60.476 52.687 96.822 2.572
6:45 62.255 54.096 96.849 2.627
6:50 64.038 55.603 96.878 2.684
6:55 65.824 57.141 96.906 2.743
7:00 67.611 58.733 96.936 2.803
7:05 69.410 60.372 96.967 2.865
7:10 71.226 62.053 96.997 2.928
7:15 73.057 63.272 97.020 2.993
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
7:20 74.912 64.525 97.042 3.062
7:25 76.793 65.858 97.066 3.136
7:30 78.697 67.266 97.091 3.213
7:35 80.632 68.744 97.117 3.293
7:40 82.599 70.289 97.144 3.376
7:45 84.596 71.898 97.173 3.462
7:50 86.629 73.568 97.201 3.551
7:55 88.701 75.297 97.231 3.642
8:00 90.810 77.083 97.262 3.736
8:05 92.964 78.925 97.293 3.831
8:10 95.167 80.823 97.325 3.929
8:15 97.414 82.776 97.357 4.029
8:20 99.715 84.785 97.390 4.131
8:25 102.074 86.850 97.424 4.235
8:30 104.484 88.972 97.459 4.340
8:35 106.960 91.151 97.494 4.448
8:40 109.506 93.390 97.530 4.558
8:45 112.118 95.692 97.566 4.670
8:50 114.988 98.069 97.603 4.785
8:55 118.423 100.569 97.643 4.905
9:00 122.788 103.278 97.684 5.033
9:05 128.304 106.314 97.731 5.176
9:10 134.751 109.781 97.784 5.338
9:15 141.723 113.734 97.843 5.520
9:20 148.836 118.167 97.909 5.722
9:25 155.848 123.028 97.980 5.940
9:30 162.551 127.875 98.050 6.172
9:35 168.973 132.879 98.121 6.415
9:40 175.188 138.119 98.195 6.667
9:45 181.289 143.582 98.270 6.924
9:50 187.361 149.128 98.347 7.185
9:55 193.441 154.852 98.424 7.450
10:00 199.555 160.694 98.503 7.716
10:05 205.796 166.651 98.581 7.984
10:10 212.197 172.727 98.661 8.255
10:15 218.767 178.929 98.740 8.527
10:20 225.594 185.272 98.821 8.803
10:25 232.698 191.775 98.903 9.082
10:30 240.074 198.457 98.986 9.366
10:35 247.827 205.160 99.069 9.656
10:40 255.966 212.081 99.153 9.953
10:45 264.482 219.279 99.240 10.260
10:50 273.405 226.795 99.329 10.575
10:55 282.615 234.646 99.422 10.901
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
11:00 291.931 242.791 99.516 11.234
11:05 301.306 251.196 99.613 11.576
11:10 310.675 259.821 99.711 11.923
11:15 319.971 268.529 99.811 12.275
11:20 329.620 277.256 99.912 12.632
11:25 340.167 286.231 100.015 12.998
11:30 352.242 295.411 100.120 13.380
11:35 368.108 305.405 100.232 13.791
11:40 390.074 316.887 100.360 14.258
11:45 420.730 330.830 100.514 14.819
11:50 471.614 349.163 100.713 15.548
11:55 555.565 375.845 100.998 16.587
12:00 687.599 404.017 101.416 18.169
12:05 859.621 434.470 102.057 20.606
12:10 1034.337 490.185 102.906 23.961
12:15 1163.761 556.259 103.866 27.917
12:20 1216.915 615.148 104.823 32.074
12:25 1201.904 968.024 105.493 35.113
12:30 1136.026 1132.482 105.645 35.811
12:35 1041.924 1092.485 105.609 35.649
12:40 940.832 1001.905 105.526 35.265
12:45 851.133 911.116 105.435 34.848
12:50 777.011 832.451 105.349 34.450
12:55 714.891 766.942 105.268 34.080
13:00 662.104 712.473 105.191 33.727
13:05 618.028 668.052 105.116 33.382
13:10 581.999 634.703 105.039 33.028
13:15 552.762 622.241 104.945 32.607
13:20 528.790 615.100 104.822 32.071
13:25 508.863 606.557 104.677 31.437
13:30 491.919 597.002 104.518 30.739
13:35 477.000 586.710 104.349 29.999
13:40 463.681 575.884 104.174 29.235
13:45 451.661 564.672 103.997 28.459
13:50 440.583 552.609 103.810 27.685
13:55 430.311 540.435 103.625 26.920
14:00 420.795 528.241 103.444 26.170
14:05 411.928 516.103 103.268 25.442
14:10 403.662 504.090 103.098 24.737
14:15 396.060 492.047 102.932 24.061
14:20 389.035 479.963 102.769 23.417
14:25 382.593 468.259 102.615 22.809
14:30 376.689 456.986 102.470 22.237
14:35 371.136 446.675 102.334 21.701
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
14:40 365.881 440.975 102.203 21.182
14:45 360.936 435.174 102.072 20.668
14:50 355.782 429.187 101.941 20.159
14:55 349.769 422.966 101.808 19.655
15:00 342.156 416.579 101.674 19.146
15:05 332.542 409.899 101.536 18.624
15:10 321.549 402.825 101.391 18.077
15:15 310.162 395.300 101.240 17.505
15:20 299.182 384.057 101.084 16.914
15:25 289.130 369.589 100.932 16.345
15:30 280.430 355.825 100.785 15.810
15:35 273.038 343.192 100.648 15.310
15:40 266.720 331.515 100.521 14.846
15:45 261.224 320.838 100.404 14.417
15:50 256.385 311.117 100.296 14.024
15:55 252.099 302.275 100.197 13.662
16:00 248.280 294.241 100.106 13.331
16:05 244.796 286.942 100.023 13.028
16:10 241.588 280.150 99.945 12.750
16:15 238.629 273.914 99.873 12.496
16:20 235.859 268.236 99.807 12.263
16:25 233.251 262.984 99.747 12.049
16:30 230.797 258.075 99.691 11.853
16:35 228.461 253.588 99.640 11.672
16:40 226.251 249.472 99.593 11.506
16:45 224.190 245.675 99.549 11.352
16:50 222.258 242.174 99.509 11.209
16:55 220.425 238.938 99.471 11.077
17:00 218.661 235.935 99.437 10.954
17:05 216.917 233.137 99.404 10.838
17:10 215.199 230.511 99.373 10.730
17:15 213.531 228.037 99.344 10.627
17:20 211.908 225.697 99.316 10.530
17:25 210.330 223.534 99.290 10.437
17:30 208.799 221.367 99.265 10.348
17:35 207.288 219.359 99.241 10.263
17:40 205.796 217.433 99.218 10.181
17:45 204.339 215.579 99.196 10.103
17:50 202.655 213.773 99.174 10.026
17:55 200.351 211.942 99.152 9.947
18:00 196.973 209.967 99.128 9.863
18:05 192.285 207.691 99.100 9.765
18:10 186.649 204.998 99.067 9.649
18:15 180.686 201.858 99.028 9.513
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
18:20 174.923 198.297 98.984 9.359
18:25 169.673 194.389 98.936 9.194
18:30 165.179 190.363 98.885 9.022
18:35 161.430 186.347 98.835 8.849
18:40 158.318 182.445 98.785 8.680
18:45 155.697 178.719 98.738 8.518
18:50 153.485 175.208 98.693 8.364
18:55 151.601 171.928 98.650 8.219
19:00 149.969 168.887 98.611 8.084
19:05 148.498 166.074 98.574 7.958
19:10 147.156 163.476 98.539 7.842
19:15 145.937 161.078 98.508 7.733
19:20 144.822 158.863 98.478 7.633
19:25 143.785 156.818 98.451 7.540
19:30 142.797 154.925 98.425 7.453
19:35 141.821 153.166 98.402 7.372
19:40 140.860 151.523 98.380 7.296
19:45 139.934 149.982 98.359 7.225
19:50 139.057 148.534 98.339 7.158
19:55 138.226 147.224 98.320 7.094
20:00 137.442 145.903 98.303 7.034
20:05 136.684 144.683 98.286 6.977
20:10 135.951 143.568 98.270 6.924
20:15 135.250 142.509 98.255 6.872
20:20 134.577 141.418 98.241 6.824
20:25 133.923 140.447 98.228 6.778
20:30 133.279 139.521 98.215 6.734
20:35 132.629 138.635 98.202 6.692
20:40 131.976 137.783 98.190 6.651
20:45 131.335 136.960 98.179 6.612
20:50 130.714 136.163 98.168 6.573
20:55 130.123 135.394 98.157 6.537
21:00 129.569 134.652 98.146 6.501
21:05 129.038 133.939 98.136 6.467
21:10 128.514 133.251 98.126 6.433
21:15 127.975 132.585 98.117 6.401
21:20 127.406 131.935 98.108 6.370
21:25 126.815 131.295 98.099 6.339
21:30 126.222 130.662 98.090 6.308
21:35 125.638 130.037 98.081 6.277
21:40 125.074 129.419 98.072 6.247
21:45 124.540 128.811 98.063 6.218
21:50 124.032 128.215 98.055 6.189
21:55 123.545 127.633 98.046 6.160
Time Inflow (cfs)
Outflow
(cfs) Elevation
Storage
(AC‐FT)
Double Box Culvert Outlet and Storage [100‐year]
22:00 123.076 127.066 98.038 6.132
22:05 122.619 126.513 98.030 6.105
22:10 122.171 125.974 98.023 6.079
22:15 121.734 125.448 98.015 6.053
22:20 121.294 124.934 98.007 6.027
22:25 120.836 124.430 98.000 6.003
22:30 120.348 123.880 97.992 5.978
22:35 119.825 123.335 97.984 5.954
22:40 119.289 122.794 97.976 5.930
22:45 118.779 122.256 97.969 5.906
22:50 118.316 121.726 97.961 5.882
22:55 117.903 121.210 97.953 5.859
23:00 117.530 120.712 97.946 5.836
23:05 117.177 120.234 97.939 5.815
23:10 116.828 119.774 97.932 5.794
23:15 116.471 119.331 97.926 5.774
23:20 116.101 118.898 97.919 5.755
23:25 115.719 118.475 97.913 5.736
23:30 115.332 118.057 97.907 5.717
23:35 114.937 117.644 97.901 5.698
23:40 114.536 117.234 97.895 5.679
23:45 114.133 116.824 97.889 5.661
APPENDIX H.2
Existing Froom Creek Hydrologic Analysis
This Page Intentionally Left Blank.
HYDROLOGIC ANALYSIS
EXISTING FROOM CREEK
Prepared as a Supplement for the Froom Ranch Hydrology Report
for the Proposed Condition
Date: 07-16-2019
Prepared by RRM Design Group
Prepared for John and Susan Madonna Trust and Villaggio
Communities
CREATINGENVIRONMENTSPEOPLEENJOY®
Table of Contents
Page No.
1. Purpose 1
2. Background 1
3. Scope, Objective and Analysis 1-2
4. Conclusion 2
Appendix 1: Historic Condition Analysis
1.1: Aerial Imagery 2005 4
1.2: Aerial Imagery 2011 5
1.3: Cross-Section Locations Exhibit 6
1.4: HEC-RAS Cross-Section Results 7-17
1.5: Historic Froom Creek Profile 18
1.6: Historic Froom Creek Tabular Results 19
Appendix 2: Existing Condition Analysis
2.1: Aerial Imagery from 2013 21
2.2: Cross-Sections Location Exhibit 22
2.3: HEC-RAS Cross-Section Results 23-45
2.4: Existing Froom Creek Profile 46
2.5: Existing LOVR Ditch and Calle Joaquin 47
2.6: Existing Froom Creek Tabular Results 48-49
2.7: Existing Froom Creek Overbanking Results 50
1. Purpose:
The purpose of this report is to describe and analyze the Historic and Existing Froom Creek
conditions, and to compare those with the Proposed condition, with respect to periodic
overbanking of the creek banks, which flows to the existing LOVR Ditch and Calle Joaquin
Wetlands.
2. Background:
a. Historic Condition (Prior to 2013)
For the purpose of this report, the condition of Froom Creek prior to 2013 is referred to as
the ‘Historic Condition.’ Appendix I of this report analyzes the Historical Condition of the
Froom Creek before 2013, and the creek bank overbanking that occurred. This analysis
confirms the overbanking conditions anticipated by Balanced Hydrologics in their report from
2005, appendix A (pg. 5). This report also details the specific water surface elevation at which
each cross-section overbanks. See Appendix 1, section D (pgs. 7-17), of this report for the
specific water surface elevations when overbanking occurs. Aerial imagery from 2005 and 2011
(pg. 4-5) is provided to show the creek condition before the addition of the artificial berm
placed after 2013 (see pg. 21).
b. Existing Condition (2013 to Present)
In or around 2013, an artificial berm was placed along the eastern bank of Froom Creek. The
analysis of the Existing Froom Creek is included in this report, Appendix 2. Overbanking is
significantly reduced and occurs at a much higher flowrate when compared to the Historic
Condition; See Appendix 2, Section C (pgs. 23-45). Aerial imagery from 2013 (pg. 21) has been
provided to show the visible change to the creek due to the added embankment.
The Froom Creek Channel receives water from watershed indexes #4 (Froom Creek Top) and
#5 (Froom Creek Upper) (see report titled “Preliminary Hydrologic and Hydraulic
Calculations,” Appendix 3, prepared by RRM Design Group, dated February 22, 2019). The
parallel channel, comprised of the LOVR Ditch and the Calle Joaquin Wetland, receives water
from watershed indexes #8 (Home Depot + Costco), #9 (Irish Hills), and occasionally from the
Existing Froom Creek when overbanking occurs.
3. Scope, Objectives, and Analysis:
a. Scope:
The Historic Condition was analyzed conveying the flow from watershed indexes #4 (Froom
Creek Top) and #5 (Froom Creek Upper). The cross-sections used in this analysis only
consider the extents of the Historic Froom Creek channel to accurately depict where
overbanking occurs.
Page 1
The Existing Condition was also analyzed conveying the flow from watershed indexes #4
(Froom Creek Top) and #5 (Froom Creek Upper) in the Existing Froom Creek. The LOVR
Ditch and Calle Joaquin Wetland convey flow from watershed indexes #8 (Home Depot +
Costco), #9 (Irish Hills), and occasionally from the Existing Froom Creek when overbanking
occurs.
b. Objectives:
The objectives of this report are to describe and analyze the Historic and Existing Froom
Creek conditions, and to compare those with the Proposed condition, with respect to periodic
overbanking of the creek banks, which flows to the existing LOVR Ditch and Calle Joaquin
Wetlands.
c. Analysis:
The proposed restored Froom Creek condition will mimic the historic condition, in that the
creek will overbank only after the 2-yr peak flow is achieved. Flows greater than a 2-yr design
storm will overbank to the Calle Joaquin Wetland or be contained within the channel when not
adjacent to the wetland. This is much like the Historical Condition, which had no artificial berm
placed adjacent to the creek. See table below for a summary comparison of the three
conditions and when Froom Creek overbanking occurs.
4. Conclusion:
With the exception of a two-year design storm, the Proposed Condition overflows at similar
flowrates compared to the Historic Condition. The two-year design storm is contained within a
low flow swale, as required by the City of San Luis Obispo, per the Drainage Design Manual.
The Existing Condition overbanking flowrates are reduced due to the artificial berm placed
adjacent to Froom Creek. In summary, the proposed development achieves the objective of
returning the watershed to the historic condition.
Historic Existing Proposed
2-yr 253.3 (100) 253.3 (0) 518.7 (0)
10-yr 521.5 (318) 521.5 (89.4) 707.3 (188.6)
25-yr 714.3 (475.2) 714.3 (282.2) 877.2 (358.5)
50-yr 867.6 (599.3) 867.6 (435.5) 1098.1 (579.4)
100-yr 980.4 (691) 980.4 (548.3) 1240.8 (722.1)
Total Creek Flow (Overbank Flowrate) (cfs)
Page 2
Appendix 1: Historic Condition Analysis
Page 3
1000 ft
N➤➤NPage 4
No Artificial Berm Placed
Adjacent to Creek
Froom Creek - Historic Condition
2005 Froom Creek AerialPage 4
1000 ft
N➤➤NPage 5
No Artificial Berm Placed
Adjacent to Creek
Froom Creek - Historic Condition
2011 Froom Creek Aerial
Detention Basins Added
Page 5
Page 6
0102030405060108109110111112113Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 272.83 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 1Page 7
0510152025109110111112113114115Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 401.44 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 2Page 8
051015202530108110112114116118Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 535.09 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 3Page 9
0246810121416112113114115116117118Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 770.3 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 4Page 10
051015202530112113114115116117118119120121Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 916.4 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 5Page 11
05101520253035115116117118119120121Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1191.25 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 6Page 12
0510152025117118119120121122Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1387.15 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 7Page 13
0510152025303540121122123124125126127Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1695.61 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 8Page 14
05101520253035125126127128129130Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1921.22 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 9Page 15
0510152025125126127128129130131132Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 2096.2 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 10Page 16
0102030405060132133134135136137138Creek Only Plan: Plan 01 6/10/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 2444.37 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Historic Froom CreekCross Section: 11Page 17
05001000150020002500105110115120125130135140Creek Only Plan: Plan 01 6/10/2019 Main Channel Distance (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundExisting Froom C Froom Creek ExisHistoric Froom Creek ProfileSection 11Section 1Page 18
HEC-RAS Plan: Plan 01 River: Existing Froom C Reach: Froom Creek Exis
Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl
(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)
Froom Creek Exis 2444.37 2-yr 201.93 132.66 134.74 134.74 135.26 0.018234 5.83 34.62 33.42 1.01
Froom Creek Exis 2444.37 10-yr 419.94 132.66 135.44 135.44 136.17 0.016390 6.86 61.18 42.57 1.01
Froom Creek Exis 2444.37 25-yr 577.16 132.66 135.80 135.80 136.67 0.015272 7.51 76.90 44.00 1.00
Froom Creek Exis 2444.37 50-yr 701.37 132.66 136.04 136.04 137.03 0.014997 7.99 87.73 44.78 1.01
Froom Creek Exis 2444.37 100-yr 792.91 132.66 136.22 136.22 137.29 0.014584 8.27 95.87 45.35 1.00
Froom Creek Exis 2096.2 2-yr 201.93 125.91 128.87 129.17 0.004504 4.44 45.52 20.61 0.53
Froom Creek Exis 2096.2 10-yr 419.94 125.91 129.97 130.56 0.005713 6.16 68.17 20.61 0.60
Froom Creek Exis 2096.2 25-yr 577.16 125.91 130.56 131.36 0.006599 7.17 80.46 20.61 0.64
Froom Creek Exis 2096.2 50-yr 701.37 125.91 130.96 131.93 0.007348 7.92 88.59 20.61 0.67
Froom Creek Exis 2096.2 100-yr 792.91 125.91 131.21 132.32 0.007954 8.45 93.79 20.61 0.70
Froom Creek Exis 1921.22 2-yr 201.93 125.00 127.06 127.06 127.74 0.017815 6.61 30.55 23.03 1.01
Froom Creek Exis 1921.22 10-yr 419.94 125.00 127.94 127.94 128.95 0.016096 8.04 52.22 26.41 1.01
Froom Creek Exis 1921.22 25-yr 577.16 125.00 128.45 128.45 129.63 0.015527 8.73 66.09 28.37 1.01
Froom Creek Exis 1921.22 50-yr 701.37 125.00 128.81 128.81 130.11 0.015168 9.17 76.51 29.77 1.01
Froom Creek Exis 1921.22 100-yr 792.91 125.00 129.06 129.06 130.44 0.014857 9.42 84.18 30.81 1.00
Froom Creek Exis 1695.61 2-yr 201.93 121.57 123.89 124.24 0.008535 4.77 42.37 30.30 0.71
Froom Creek Exis 1695.61 10-yr 419.94 121.57 124.81 125.31 0.007637 5.66 74.16 36.82 0.70
Froom Creek Exis 1695.61 25-yr 577.16 121.57 125.34 125.93 0.006873 6.17 93.62 36.82 0.68
Froom Creek Exis 1695.61 50-yr 701.37 121.57 125.75 126.40 0.006359 6.46 108.57 36.82 0.66
Froom Creek Exis 1695.61 100-yr 792.91 121.57 126.05 126.73 0.006021 6.64 119.48 36.82 0.65
Froom Creek Exis 1387.15 2-yr 201.93 117.71 119.86 119.86 120.57 0.017177 6.78 29.78 20.84 1.00
Froom Creek Exis 1387.15 10-yr 419.94 117.71 120.76 120.76 121.92 0.016273 8.67 48.45 20.84 1.00
Froom Creek Exis 1387.15 25-yr 577.16 117.71 121.31 121.31 122.75 0.016052 9.63 59.95 20.84 1.00
Froom Creek Exis 1387.15 50-yr 701.37 117.71 121.71 121.71 123.35 0.015996 10.27 68.31 20.84 1.00
Froom Creek Exis 1387.15 100-yr 792.91 117.71 121.99 121.99 123.77 0.016012 10.69 74.14 20.84 1.00
Froom Creek Exis 1191.25 2-yr 201.93 115.00 117.38 117.79 0.009089 5.13 39.34 26.89 0.75
Froom Creek Exis 1191.25 10-yr 419.94 115.00 118.65 119.10 0.005348 5.38 78.10 31.94 0.61
Froom Creek Exis 1191.25 25-yr 577.16 115.00 119.51 119.97 0.003953 5.47 105.54 31.94 0.53
Froom Creek Exis 1191.25 50-yr 701.37 115.00 120.17 120.65 0.003328 5.53 126.74 31.94 0.49
Froom Creek Exis 1191.25 100-yr 792.91 115.00 120.65 121.13 0.003014 5.59 141.97 31.94 0.47
Froom Creek Exis 916.4 2-yr 201.93 112.99 116.31 116.50 0.002647 3.47 58.19 25.63 0.41
Froom Creek Exis 916.4 10-yr 419.94 112.99 117.85 118.13 0.002297 4.26 98.66 26.54 0.39
Froom Creek Exis 916.4 25-yr 577.16 112.99 118.81 119.15 0.002167 4.64 124.33 26.54 0.38
Froom Creek Exis 916.4 50-yr 701.37 112.99 119.53 119.90 0.002105 4.90 143.28 26.54 0.37
Froom Creek Exis 916.4 100-yr 792.91 112.99 120.03 120.43 0.002076 5.06 156.58 26.54 0.37
Froom Creek Exis 770.3 2-yr 201.93 112.00 114.72 114.72 115.62 0.017780 7.59 26.61 15.15 1.01
Froom Creek Exis 770.3 10-yr 419.94 112.00 115.85 115.85 117.29 0.017453 9.63 43.61 15.15 1.00
Froom Creek Exis 770.3 25-yr 577.16 112.00 116.53 116.53 118.31 0.017744 10.69 53.97 15.15 1.00
Froom Creek Exis 770.3 50-yr 701.37 112.00 117.02 117.02 119.05 0.018138 11.42 61.39 15.15 1.00
Froom Creek Exis 770.3 100-yr 792.91 112.00 117.37 117.37 119.57 0.018358 11.89 66.68 15.15 1.00
Froom Creek Exis 535.09 2-yr 253.28 109.00 113.70 113.87 0.001814 3.30 76.84 28.32 0.35
Froom Creek Exis 535.09 10-yr 521.50 109.00 115.28 115.57 0.001899 4.29 121.50 28.32 0.37
Froom Creek Exis 535.09 25-yr 714.26 109.00 116.21 116.57 0.001992 4.84 147.70 28.32 0.37
Froom Creek Exis 535.09 50-yr 867.58 109.00 116.88 117.30 0.002055 5.20 166.87 28.32 0.38
Froom Creek Exis 535.09 100-yr 980.40 109.00 117.35 117.81 0.002098 5.44 180.24 28.32 0.38
Froom Creek Exis 401.44 2-yr 253.28 109.00 112.27 112.27 113.24 0.017113 7.89 32.11 16.88 1.01
Froom Creek Exis 401.44 10-yr 521.50 109.00 113.53 113.53 114.90 0.016043 9.39 55.56 20.30 1.00
Froom Creek Exis 401.44 25-yr 714.26 109.00 114.17 114.17 115.85 0.016020 10.42 68.54 20.30 1.00
Froom Creek Exis 401.44 50-yr 867.58 109.00 114.63 114.63 116.55 0.016125 11.13 77.98 20.30 1.00
Froom Creek Exis 401.44 100-yr 980.40 109.00 114.96 114.96 117.04 0.016210 11.59 84.61 20.30 1.00
Froom Creek Exis 272.83 2-yr 253.28 108.41 110.86 110.61 111.25 0.010002 4.96 51.10 40.17 0.77
Froom Creek Exis 272.83 10-yr 521.50 108.41 111.63 111.39 112.19 0.010003 6.00 86.97 50.96 0.81
Froom Creek Exis 272.83 25-yr 714.26 108.41 112.00 111.75 112.71 0.010002 6.73 106.20 51.83 0.83
Froom Creek Exis 272.83 50-yr 867.58 108.41 112.27 112.01 113.08 0.010019 7.25 119.74 51.83 0.84
Froom Creek Exis 272.83 100-yr 980.40 108.41 112.45 112.19 113.34 0.010017 7.59 129.21 51.83 0.85
Historic Froom Creek Tabular Results
Page 19
Appendix 2: Existing Condition Analysis
Page 20
1000 ft
N➤➤NPage 21
New Artificial Berm Placed
Adjacent to Creek
Froom Creek - Existing Condition
2013 Froom Creek AerialPage 21
Page 22
020406080100120140108110112114116118Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 272.83 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 1Page 23
020406080100120140160180108110112114116118120Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 401.44 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 2Page 24
020406080109110111112113114115116Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 535.09 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 3Page 25
0102030405060112114116118120122Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 770.3 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 4Page 26
020406080100120112114116118120122124126Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 916.4 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 5Page 27
050100150200114116118120122124Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1191.25 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 6Page 28
020406080100117118119120121122123124125Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1387.15 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 7Page 29
050100150200250120122124126128130132Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1695.61 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 8Page 30
020406080100120140160125126127128129130131132Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 1921.22 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 9Page 31
020406080100120140124126128130132134136Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 2096.2 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 10Page 32
020406080100120140132134136138140142Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Froom Creek Exis RS = 2444.37 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Froom CreekCross Section: 11Page 33
020406080100120140160106.5107.0107.5108.0108.5109.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 115.55 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 1Page 34
050100150200250300350106.0106.5107.0107.5108.0108.5109.0109.5Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 169 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 2Page 35
0100200300400500106.0106.5107.0107.5108.0108.5109.0109.5Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 205.35 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 3Page 36
050100150200250300350400106.0106.5107.0107.5108.0108.5109.0109.5Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 318.73 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 4Page 37
0100200300400500106.0106.5107.0107.5108.0108.5109.0109.5110.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 440.14 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 5Page 38
050100150200250300350108.0108.5109.0109.5110.0110.5111.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 741.18 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035Existing Calle Joaquin WetlandCross Section: 6Page 39
050100150200250110.0110.5111.0111.5112.0112.5113.0113.5114.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 1437.42 Station (ft)Elevation (ft)LegendWS 10-yrWS 2-yrWS 25-yrWS 100-yrWS 50-yrGroundBank Sta.035.035Existing LOVR DitchCross Section: 7Page 40
0100200300400500113.5114.0114.5115.0115.5116.0116.5117.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 1654.9 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035.035Existing LOVR DitchCross Section: 8Page 41
050100150200250300350400116.0116.5117.0117.5118.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 1993.69 Station (ft)Elevation (ft)LegendWS 25-yrWS 10-yrWS 100-yrWS 50-yrWS 2-yrGroundBank Sta.035Existing LOVR DitchCross Section: 9Page 42
050100150200250300350400116.0116.5117.0117.5118.0118.5119.0119.5120.0Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 2201.97 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035.035Existing LOVR DitchCross Section: 10Page 43
050100150200250300350400117.0117.5118.0118.5119.0119.5120.0120.5Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 2413.92 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035.035Existing LOVR DitchCross Section: 11Page 44
020406080100120140118119120121122123124Existing Froom Creek Model Plan: Plan 01 6/13/2019 River = Existing Froom C Reach = Wetland RS = 2794.8 Station (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundBank Sta.035.035Existing LOVR DitchCross Section: 12Page 45
05001000150020002500105110115120125130135140Existing Froom Creek Model Plan: Plan 01 6/10/2019 Main Channel Distance (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundExisting Froom C Froom Creek ExisExisting Froom Creek ProfileSection 11Section 1Page 46
050010001500200025003000106108110112114116118120Existing Froom Creek Model Plan: Plan 01 6/11/2019 Main Channel Distance (ft)Elevation (ft)LegendWS 100-yrWS 50-yrWS 25-yrWS 10-yrWS 2-yrGroundExisting Froom C WetlandExisting LOVR Ditch and Calle JoaquinWetland ProfileSection 12Section 1Page 47
HEC-RAS Plan: .Plan 01
Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl
(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)
Froom Creek Exis 2444.37 2-yr 201.93 132.66 134.73 134.73 135.26 0.018466 5.86 34.47 33.36 1.02
Froom Creek Exis 2444.37 10-yr 419.94 132.66 135.43 135.43 136.17 0.016526 6.89 60.95 42.41 1.01
Froom Creek Exis 2444.37 25-yr 577.16 132.66 135.83 135.83 136.66 0.015700 7.28 79.23 48.81 1.01
Froom Creek Exis 2444.37 50-yr 701.37 132.66 136.09 136.09 136.99 0.015386 7.61 92.17 52.38 1.01
Froom Creek Exis 2444.37 100-yr 792.91 132.66 136.26 136.26 137.21 0.015003 7.83 101.22 54.03 1.01
Froom Creek Exis 2096.2 2-yr 201.93 125.91 128.88 129.07 0.005310 3.49 57.88 47.27 0.56
Froom Creek Exis 2096.2 10-yr 419.94 125.91 129.61 129.88 0.006130 4.21 99.65 68.65 0.62
Froom Creek Exis 2096.2 25-yr 577.16 125.91 129.96 130.29 0.006367 4.57 126.16 79.17 0.64
Froom Creek Exis 2096.2 50-yr 701.37 125.91 130.18 130.55 0.006449 4.88 143.65 82.55 0.65
Froom Creek Exis 2096.2 100-yr 792.91 125.91 130.32 130.73 0.006497 5.09 155.64 84.39 0.66
Froom Creek Exis 1921.22 2-yr 201.93 125.00 127.00 127.00 127.44 0.019712 5.32 37.97 44.70 1.02
Froom Creek Exis 1921.22 10-yr 419.94 125.00 127.59 127.59 128.17 0.017302 6.08 69.05 60.29 1.00
Froom Creek Exis 1921.22 25-yr 577.16 125.00 127.90 127.90 128.56 0.016545 6.51 88.72 67.73 1.00
Froom Creek Exis 1921.22 50-yr 701.37 125.00 128.11 128.11 128.82 0.016093 6.78 103.41 72.63 1.00
Froom Creek Exis 1921.22 100-yr 792.91 125.00 128.25 128.25 129.00 0.015814 6.97 113.83 75.83 1.00
Froom Creek Exis 1695.61 2-yr 201.93 121.57 123.87 124.17 0.008370 4.38 46.08 38.13 0.70
Froom Creek Exis 1695.61 10-yr 419.94 121.57 124.76 125.00 0.008282 3.95 106.41 102.70 0.68
Froom Creek Exis 1695.61 25-yr 577.16 121.57 125.15 125.37 0.007778 3.76 153.34 151.71 0.66
Froom Creek Exis 1695.61 50-yr 701.37 121.57 125.32 125.56 0.007361 3.92 178.91 159.80 0.65
Froom Creek Exis 1695.61 100-yr 792.91 121.57 125.43 125.68 0.007067 4.02 197.05 164.16 0.65
Froom Creek Exis 1387.15 2-yr 201.93 117.71 119.89 119.89 120.51 0.017672 6.36 31.77 26.18 1.02
Froom Creek Exis 1387.15 10-yr 419.94 117.71 120.76 120.76 121.51 0.015888 6.95 60.41 40.29 1.00
Froom Creek Exis 1387.15 25-yr 577.16 117.71 121.16 121.16 122.01 0.015632 7.40 78.00 46.83 1.01
Froom Creek Exis 1387.15 50-yr 701.37 117.71 121.45 121.45 122.35 0.014926 7.62 92.03 51.06 1.00
Froom Creek Exis 1387.15 100-yr 792.91 117.71 121.63 121.63 122.58 0.014684 7.80 101.61 53.76 1.00
Froom Creek Exis 1191.25 2-yr 201.93 115.00 117.43 117.81 0.008375 4.98 40.53 27.23 0.72
Froom Creek Exis 1191.25 10-yr 419.94 115.00 118.51 118.99 0.007380 5.57 75.36 38.90 0.71
Froom Creek Exis 1191.25 25-yr 577.16 115.00 119.15 118.44 119.64 0.006428 5.58 103.36 48.06 0.67
Froom Creek Exis 1191.25 50-yr 701.37 115.00 119.45 119.99 0.006798 5.94 118.10 52.25 0.70
Froom Creek Exis 1191.25 100-yr 792.91 115.00 119.65 120.23 0.006975 6.16 128.82 55.09 0.71
Froom Creek Exis 916.4 2-yr 201.93 112.99 116.31 116.48 0.002911 3.25 62.22 34.41 0.43
Froom Creek Exis 916.4 10-yr 419.94 112.99 117.50 117.72 0.002857 3.73 112.61 50.60 0.44
Froom Creek Exis 916.4 25-yr 577.16 112.99 118.08 118.33 0.003344 3.99 144.70 66.79 0.48
Froom Creek Exis 916.4 50-yr 701.37 112.99 118.40 118.67 0.003209 4.23 166.00 67.83 0.48
Froom Creek Exis 916.4 100-yr 792.91 112.99 118.62 118.92 0.003121 4.38 181.17 68.57 0.47
Froom Creek Exis 770.3 2-yr 201.93 112.00 114.80 114.80 115.57 0.016881 7.03 28.72 18.73 1.00
Froom Creek Exis 770.3 10-yr 419.94 112.00 115.87 115.87 116.83 0.015062 7.85 53.50 27.43 0.99
Froom Creek Exis 770.3 25-yr 577.16 112.00 116.46 116.46 117.35 0.015793 7.56 76.31 43.17 1.00
Froom Creek Exis 770.3 50-yr 701.37 112.00 116.70 116.70 117.71 0.015594 8.07 86.94 43.99 1.01
Froom Creek Exis 770.3 100-yr 792.91 112.00 116.87 116.87 117.97 0.015547 8.41 94.26 44.55 1.02
Froom Creek Exis 535.09 2-yr 253.28 109.00 113.57 113.74 0.002594 3.32 76.26 38.65 0.42
Froom Creek Exis 535.09 10-yr 521.50 109.00 114.77 114.99 0.003058 3.78 138.13 65.61 0.46
Froom Creek Exis 535.09 25-yr 714.26 109.00 115.30 115.56 0.002965 4.08 174.98 71.91 0.46
Froom Creek Exis 535.09 50-yr 867.58 109.00 115.67 115.95 0.002943 4.30 201.92 76.19 0.47
Froom Creek Exis 535.09 100-yr 980.40 109.00 115.88 116.19 0.002940 4.49 218.32 76.70 0.47
Froom Creek Exis 401.44 2-yr 253.28 109.00 112.27 112.27 112.98 0.016648 6.74 37.57 26.48 1.00
Froom Creek Exis 401.44 10-yr 521.50 109.00 113.23 113.23 114.13 0.015455 7.64 68.24 37.91 1.00
Froom Creek Exis 401.44 25-yr 714.26 109.00 113.72 113.72 114.73 0.015083 8.03 88.91 45.17 1.01
Froom Creek Exis 401.44 50-yr 867.58 109.00 114.08 114.08 115.13 0.014572 8.23 105.46 50.23 1.00
Froom Creek Exis 401.44 100-yr 980.40 109.00 114.38 114.38 115.38 0.014803 8.01 122.47 61.54 1.00
Froom Creek Exis 272.83 2-yr 253.28 108.41 110.86 110.61 111.25 0.010001 4.96 51.10 40.17 0.77
Froom Creek Exis 272.83 10-yr 521.50 108.41 111.76 111.48 112.17 0.010004 5.10 102.17 77.07 0.78
Froom Creek Exis 272.83 25-yr 714.26 108.41 112.10 111.84 112.57 0.010003 5.50 129.96 87.76 0.80
Froom Creek Exis 272.83 50-yr 867.58 108.41 112.30 112.06 112.83 0.010016 5.87 147.74 90.39 0.81
Froom Creek Exis 272.83 100-yr 980.40 108.41 112.43 112.19 113.02 0.010012 6.12 160.25 92.16 0.82
Wetland 2794.8 2-yr 15.86 118.00 119.19 118.73 119.24 0.002682 1.70 9.30 13.37 0.36
Wetland 2794.8 10-yr 23.68 118.00 119.36 118.89 119.43 0.003198 2.01 11.75 15.00 0.40
Wetland 2794.8 25-yr 27.49 118.00 119.44 118.95 119.51 0.003387 2.14 12.86 15.68 0.42
Wetland 2794.8 50-yr 30.78 118.00 119.50 119.00 119.58 0.003403 2.20 13.97 16.34 0.42
Wetland 2794.8 100-yr 34.04 118.00 119.56 119.05 119.64 0.003496 2.28 14.92 16.88 0.43
Wetland 2413.92 2-yr 15.86 117.27 117.49 117.51 0.009060 1.19 13.34 83.53 0.52
Wetland 2413.92 10-yr 23.68 117.27 117.54 117.46 117.57 0.008093 1.33 17.79 86.41 0.52
Wetland 2413.92 25-yr 27.49 117.27 117.56 117.59 0.008013 1.41 19.55 86.80 0.52
Wetland 2413.92 50-yr 30.78 117.27 117.57 117.61 0.008595 1.50 20.51 87.06 0.55
Wetland 2413.92 100-yr 34.04 117.27 117.59 117.50 117.63 0.008729 1.56 21.76 87.82 0.55
Wetland 2201.97 2-yr 15.86 116.28 116.81 116.82 0.001641 0.70 22.63 86.98 0.24
Wetland 2201.97 10-yr 23.68 116.28 116.89 116.90 0.001678 0.77 30.69 105.93 0.25
Wetland 2201.97 25-yr 27.49 116.28 116.93 116.94 0.001608 0.79 35.08 115.03 0.25
Wetland 2201.97 50-yr 30.78 116.28 116.97 116.98 0.001433 0.77 40.08 124.35 0.24
Wetland 2201.97 100-yr 34.04 116.28 117.00 117.01 0.001428 0.79 43.42 130.20 0.24
Existing Froom Creek Tabular Results (1)
Page 48
HEC-RAS Plan: .Plan 01 (Continued)
Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl
(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)
Wetland 1993.69 2-yr 15.86 116.00 116.38 116.39 0.002734 0.79 20.02 93.90 0.30
Wetland 1993.69 10-yr 23.68 116.00 116.45 116.46 0.002760 0.87 27.06 110.13 0.31
Wetland 1993.69 25-yr 27.49 116.00 116.45 116.47 0.003577 1.00 27.47 110.99 0.35
Wetland 1993.69 50-yr 30.78 116.00 116.43 116.45 0.005702 1.23 25.07 105.79 0.44
Wetland 1993.69 100-yr 34.04 116.00 116.44 116.47 0.006128 1.29 26.33 108.56 0.46
Wetland 1654.9 2-yr 15.86 114.00 114.20 114.20 114.26 0.026913 1.38 8.94 78.13 0.82
Wetland 1654.9 10-yr 23.68 114.00 114.24 114.24 114.30 0.027447 1.51 12.79 104.47 0.84
Wetland 1654.9 25-yr 27.49 114.00 114.30 114.26 114.33 0.013814 1.17 20.14 150.88 0.61
Wetland 1654.9 50-yr 30.78 114.00 114.35 114.37 0.006634 0.96 28.94 176.75 0.44
Wetland 1654.9 100-yr 34.04 114.00 114.36 114.38 0.006188 0.98 31.57 178.20 0.43
Wetland 1437.42 2-yr 15.86 110.42 112.06 111.32 112.08 0.002035 0.89 17.91 56.30 0.28
Wetland 1437.42 10-yr 23.68 110.42 112.17 111.49 112.19 0.002075 0.96 24.56 69.07 0.29
Wetland 1437.42 25-yr 27.49 110.42 111.92 111.56 112.00 0.008579 2.25 12.21 27.57 0.60
Wetland 1437.42 50-yr 30.78 110.42 111.62 111.62 111.93 0.022051 4.48 6.87 10.99 1.00
Wetland 1437.42 100-yr 34.04 110.42 111.65 111.65 112.00 0.023557 4.71 7.23 11.28 1.04
Wetland 741.18 2-yr 15.86 108.00 108.36 108.36 108.45 0.032518 2.42 6.54 36.65 1.01
Wetland 741.18 10-yr 23.68 108.00 108.42 108.42 108.53 0.030880 2.63 8.99 42.83 1.01
Wetland 741.18 25-yr 27.49 108.00 108.69 108.71 0.002943 1.12 24.51 72.02 0.34
Wetland 741.18 50-yr 30.78 108.00 108.98 108.99 0.000595 0.59 52.19 121.27 0.16
Wetland 741.18 100-yr 34.04 108.00 109.16 109.17 0.000280 0.44 77.13 157.16 0.11
Wetland 440.14 2-yr 15.86 106.37 107.34 107.34 0.000049 0.19 83.46 164.15 0.05
Wetland 440.14 10-yr 23.68 106.37 108.17 108.17 0.000004 0.08 279.81 286.72 0.02
Wetland 440.14 25-yr 27.49 106.37 108.70 108.70 0.000001 0.06 446.07 333.12 0.01
Wetland 440.14 50-yr 154.99 106.37 108.98 108.98 0.000026 0.29 539.73 355.45 0.04
Wetland 440.14 100-yr 249.79 106.37 109.15 109.15 0.000050 0.42 601.47 372.06 0.06
Wetland 318.73 2-yr 15.86 106.00 107.33 107.33 0.000006 0.09 181.44 241.37 0.02
Wetland 318.73 10-yr 23.68 106.00 108.17 108.17 0.000001 0.06 415.05 311.26 0.01
Wetland 318.73 25-yr 184.65 106.00 108.70 108.70 0.000027 0.31 593.03 357.78 0.04
Wetland 318.73 50-yr 312.15 106.00 108.97 108.97 0.000050 0.45 691.57 372.30 0.06
Wetland 318.73 100-yr 406.95 106.00 109.14 109.14 0.000063 0.54 753.93 372.30 0.07
Wetland 205.35 2-yr 15.86 106.00 107.33 107.33 0.000005 0.08 189.34 242.51 0.02
Wetland 205.35 10-yr 157.79 106.00 108.16 108.16 0.000051 0.36 444.33 349.79 0.06
Wetland 205.35 25-yr 354.36 106.00 108.69 108.70 0.000086 0.55 639.13 383.37 0.08
Wetland 205.35 50-yr 510.97 106.00 108.95 108.96 0.000114 0.69 741.89 394.26 0.09
Wetland 205.35 100-yr 627.14 106.00 109.12 109.13 0.000132 0.78 807.50 402.20 0.10
Wetland 169 2-yr 15.86 106.00 107.33 107.33 0.000005 0.08 195.96 255.54 0.02
Wetland 169 10-yr 157.79 106.00 108.16 108.16 0.000047 0.37 423.63 293.43 0.05
Wetland 169 25-yr 354.36 106.00 108.69 108.69 0.000091 0.61 585.17 318.94 0.08
Wetland 169 50-yr 510.97 106.00 108.95 108.96 0.000122 0.76 668.85 318.94 0.09
Wetland 169 100-yr 627.14 106.00 109.11 109.12 0.000143 0.87 720.99 318.94 0.10
Wetland 115.55 2-yr 15.86 106.93 107.28 107.20 107.33 0.010019 1.68 9.41 37.68 0.59
Wetland 115.55 10-yr 157.79 106.93 107.98 107.81 108.14 0.009992 3.16 49.96 77.70 0.69
Wetland 115.55 25-yr 354.36 106.93 108.46 108.24 108.66 0.010001 3.56 99.60 129.73 0.72
Wetland 115.55 50-yr 510.97 106.93 108.68 108.49 108.91 0.010004 3.92 130.47 146.85 0.73
Wetland 115.55 100-yr 627.14 106.93 108.79 108.61 109.07 0.010002 4.25 147.63 146.85 0.75
Existing Froom Creek Tabular Results (2)
Page 49
Section QTotal (cfs) Qoverflow (cfs)Section Qtotal (cfs)
1 980.4 0.0 1 627.1
2 980.4 266.4 2 627.1
3 980.4 593.1 3 627.1
4 792.9 372.9 4 407.0
5 792.9 252.9 5 287.0
6 792.9 0.0 6 34.0
7 792.9 0.0 7 34.0
8 792.9 0.0 8 34.0
9 792.9 0.0 9 34.0
10 792.9 0.0 10 34.0
11 792.9 0.0 11 34.0
12 34.0
Existing Froom Creek Existing Wetland
Existing (After 2013) Froom Creek Analysis (100-yr Event)
Page 50
APPENDIX H.3
Preliminary Sediment Transportation Analysis and Calculations
This Page Intentionally Left Blank.
PRELIMINARYSEDIMENT TRANSPORT
ANALYSIS AND CALCULATIONS
Prepared as a Supplement for the Froom Ranch Hydrology Report
for the Proposed Condition
Date: 07-16-2019
Prepared by RRM Design Group
Prepared for John and Susan Madonna Trust and Villaggio
Communities
CREATING
ENVIRONMENTS
PEOPLE
ENJOY®
Table of Contents
1. Introduction Page No.
1.1: Introduction 1
2. Method & Assumptions
2.1: Modeling Software 1
2.2: Geometry 1
2.3: Hydrology 1-2
2.4: Sediment 2-3
2.5: Quasi-Unsteady Flow 3
3. Sediment
3.1: Sediment Inputs 3
3.2: Computational Increment 4
3.3: Sediment Gradation 4
3.4: Allowable Depth of Scour and Erodible Bed Limits 4
4. Analysis Results 4
5. Conclusion 4-5
Appendix I 6-31
1
1. Introduction
At the request of the City of San Luis Obispo, RRM Design Group has prepared a sediment transport
model of the Proposed Condition of Froom Creek. The sediment transport model analyzes the proposed
Froom Creek low-flow channel, which has the capacity to carry a 2-year storm event. A one-dimensional
sediment transport model has been developed to address the following primary questions related to
reaching the primary project goals:
1. What is the anticipated spatial and temporal distribution of deposited sediment?
2. Will the proposed low-flow channel erode and ultimately flow to the adjacent Calle Joaquin
Wetland?
Since this is a new creek corridor, there is a lack of measured sediment discharge and geometric data
over time. Because of this, the model cannot be calibrated to match any sort of observed historic
conditions. This analysis is based on historical rainfall data, dating back to October 2016. The model
represents anticipated erosivity and flow line movement in the Froom Creek low-flow channel and creek
bottom during the scenarios modeled, based on the proposed design. This model can be calibrated in
the future based on more detailed design elements in the final construction document phase.
2. Method & Assumptions
2.1: Modeling Software
The US Army Corps of Engineers (USACE) Hydrologic Engineering Center River Analysis System (HEC-RAS)
Version 5.0.3 was chosen for this analysis. The study uses both the hydraulic and sediment transport
modules within the HEC-RAS software.
The basic requirements for hydraulic calculations in HEC-RAS are channel cross sectional geometry,
Manning’s n-values for the cross sections, riverbank locations, distances between the cross sections,
flow information, and flow boundary information. The HEC-RAS sediment transport module calculates
transport capacity for non-cohesive and cohesive soil using hydraulic variables (velocity, flow depth, and
shear stress) and sediment properties.
The results from this analysis are a representation of sediment transport that is anticipated for the
proposed project. This analysis should serve to identify areas of concern and the overall impact of
sediment transport.
2.2: Geometry
The geometric data inputs for this model are derived from the proposed condition of Froom Creek,
associated with the project. This proposed condition includes a low-flow channel, which has the capacity
to carry a 2-year storm event. The proposed condition matches into the Existing Froom Creek geometric
alignment after section 1429.43 (see p. 24 for section).
2.3: Hydrology
The flow considered in this analysis is historical data from October 1, 2016 to May 31, 2019. The
proposed Froom Creek channel receives water from Watershed indexes #3, #6, and #7 (see Appendix 2
2
from report prepared by RRM Design Group, titled “Preliminary Hydrologic and Hydraulic Calculations,”
dated February 22, 2019). The total contributing area is 944.7 acres. See the graph below, which shows
the historical rainfall data.
2.4: Sediment
The sediment file provides the model with sediment data required for execution of the sediment
transport simulations. It contains the properties of both the bed material and incoming sediment loads,
which are considered consistent throughout the creek. Sediment grain sizes, grain size distributions,
sediment mass density, porosity of deposited sediment, bed material properties, and sediment loads
flowing in the creek are contained in the input files. Sediment gradation table is shown below.
Diameter (mm) % Finer
0.004 10
0.008 13
0.016 16
0.032 18
0.0625 22
0.125 29
0.25 36
0.5 43
1 50
2 50
4 50
8 50
16 50
32 50
64 60
128 80
256 100
0
2
4
6
8
10
12
Jan-16 Aug-16 Mar-17 Sep-17 Apr-18 Oct-18 May-19 Dec-19Rainfall Depth (in)Historic Rainfall Data Used in Analysis
3
Several equations are available in HEC-RAS to calculate sediment transport, bed sorting, and fall velocity.
The equation used in the model is selected on the sediment input screen. Bed sorting calculations are
required to simulate how the bed material composition may change over time. For example, if the bed
material becomes coarser due to the preferential removal of fine material it may become armored.
Once the armoring effect takes place, it protects the sub-surface sediments and limits the amount of
sediment that can be removed from the riverbed for transportation. The fall velocity is required to
determine its mobility, which is how easy it is to settle the material and to re-entrain it once settled on
the riverbed.
For this analysis the Ackers-White sediment transport function, the Active Layer sorting equation, and
the Ruby fall velocity equation were selected.
The Ackers-White sediment transport theory predicts the movement of non-cohesive sediments. The
theory contains four empirical parameters which were determined by fitting them to observed transport
data. These equations are widely used to calculate sediment transport, morphological change in
channels, the size of stable alluvial channels and to design physical models.
The Active Layer sorting equation is an active layer method, that considers two layers. The model has an
active layer thickness set to d90 by default. The Ruby fall velocity method is suitable for silt, sand, and
gravel sizes with specific gravities of around 2.65.
One of the limitations of the HEC-RAS sediment transport modeling is that only one sediment gradation
can be defined per cross-section. This is an important observation because the sediment properties on
the surface and sub-surface often differ especially if the channel has armored.
2.5: Quasi-Unsteady Flow
The quasi-unsteady flow file is used to define a flow hydrograph for the HEC-RAS model. The flows are
entered as a flow series for a specified duration. The computational increment is specified as a part of
the flow series. This increment determines how often calculations are performed.
The temperature of the creek water must be specified for calculating sediment particle fall velocities. A
constant water temperature of 55 degrees Fahrenheit was used for all simulations.
3. Sediment
3.1: Sediment Inputs
Since this is a new creek corridor, there is a lack of measured sediment discharge and geometric data
over time. Because of this, the model cannot be calibrated to match any sort of observed historic
conditions. This analysis is based on historic rainfall data, dating back to October 2016. The model
represents anticipated erosivity and flow line movement in the Froom Creek low-flow channel and creek
bottom during the scenarios modeled, based on the proposed design. This model can be calibrated in
the future based on more detailed design elements in the final construction document phase, as well as
after construction.
4
3.2: Computational Increment
For this analysis, computational increments were performed every hour. It was determined that a 60-
minute computational increment would provide the best balance between model stability and run time.
3.3: Sediment Gradation
Sediment data was entered into the program based on the anticipated sediment gradation in the
proposed condition. The proposed project seeks to add river rock to the bed of the channel to limit the
effects of erosion, scour, and sediment transport. For more details of the proposed creek bed, see
Chapter 2 of the report titled, “Preliminary Hydrologic and Hydraulic Calculations,” prepared by RRM
Design Group.
3.4: Allowable Depth of Scour and Erodible Bed Limits
HEC-RAS allows a set of maximin scour depths and erodible bed limits (horizontal extents of allowable
scour) that are applied during simulation. The scour depth limits that were tested ranges from 0 to 5
feet. The bank stations were used as boundaries for the erodible bed limits. All the results indicate
significantly less than 5 feet of scour in the final condition, so this limit is within the bounds of what
needs to be analyzed. See pages 6-31 for detailed scour depth outputs.
4. Analysis Results
The analysis results are included in Appendix I. The Froom Creek profile output (p. 7) shows the
anticipated creek profile elevation after applying the historical rain data and running the model. The
Froom Creek Cross-Section outputs (pages 8-31) show the extents of erosion that takes place in each
cross-section. Based on these results, it can be observed that the banks of Froom Creek do not erode.
The analysis results for section 1757.69 show some scour of the wetland. This model uses a manning’s
roughness coefficient of 0.035 to represent the proposed swale condition, which doesn’t account for the
vegetation in the wetland. When the of vegetation in the wetland is considered, it is anticipated that no
erosion of the wetland will take place.
The analysis also shows a significant amount of erosion at cross-section 3210.45. This section shows
significantly more scour due to the change in slope that occurs at this point in the proposed low-flow
channel. This condition has been anticipated by RRM and will be mitigated with an appropriate armoring
method along the channel of the creek.
5. Conclusion
As discussed in the introduction, there are two main questions to be address by the sediment transport
model results.
1. What is the anticipated spatial and temporal distribution of deposited sediment?
The profile output (Appendix I, p. 7) graphically shows what the anticipated creek profile will look like
after several years of rain events. As discussed earlier in the report, the armoring effect will take place,
which will limit the amount of erosion that takes place in the future. Although erosion of the creek bed
is anticipated, it will be minimal after the first few heavy rains, as evidenced by the Invert Change Vs.
5
Time graphs provided in Appendix I. All the Invert Change Vs. Time graphs show a steep decline in
sediment transport after the initial rain events. This is a result of the armoring effect, which limits
sediment transport after the fine grain soils on the surface are transported by flow.
2. Will the proposed low-flow channel erode and ultimately flow to the adjacent Calle Joaquin Wetland?
All the Froom Creek Cross-Section results show that although the flowline of the creek may erode
slightly, none of the results indicate that the creek banks will erode, or that the flow line will move
horizontally. The minimal erosion that is predicted will take place along the bed of Froom Creek, not
along the banks.
Based on the results obtained in this analysis, RRM anticipates minimal sediment transport and erosion
to occur after armoring occurs. Although some erosion of the Froom Creek bed is anticipated, RRM sees
no indication that the channel banks will erode.
6 Appendix I Proposed Froom Creek Alignment
7 Proposed Froom Creek Profile Output 0100020003000400095100105110115120125n:\2014\1014012-Froom-Ranch-SP-Il-Villaggio\Engineering\hydro\Hec Ras\Sediment Analysis\SedimentAnalysis.sed08Main Channel Distance (ft)Ch Invert El (ft)Legend01OCT2016 01:00:00-Ch Invert El (ft)31MAY2019 00:00:00-Ch Invert El (ft)Main 2-River 2Proposed FroomCreek ProfileProjected FroomCreek Profile
8 Froom Creek Cross-Section Outputs 0204060801001201401601801201221241261281301324164.67 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00004164.67Proposed Low Flow Swale
9 121121.25121.5121.75122122.25122.5Creek Bed Invert (ft)October 1, 2016 May 31, 2019Section 4164.67 - Low Flow Swale Flowline Elevation Change Over Time
10 0204060801001201181201221241261283969.73 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00003969.73Proposed Low Flow Swale
11 121.25121.5121.75122122.25Creek Bed Invert (ft)October 1, 2016 May 31, 2019Section 3969.73 - Low Flow Swale Flowline Elevation Change Over Time
12 0204060801001201161181201221241261283714.24 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00003714.24Proposed Low Flow Swale
13 116116.25116.5116.75117Creek Bed Invert (ft)October 1, 2016 May 31, 2019Section 3714.24 - Low Flow Swale Flowline Elevation Change Over Time
14 01002003004005001121141161181201221241263453.96 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00003453.96Proposed Low Flow SwaleExisting LOVR Ditch(not affected)
15 113113.25113.5113.75114Creek Bed Invert (ft)October 1, 2016 May 31, 20193453.96 - Low Flow Swale Flowline Elevation Change Over Time
16 0501001502002503001061081101121141161181203210.45 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00003210.45Proposed Low Flow SwaleSee "Analysis Results" on Pg. 4
17 106106.5107107.5108108.5109109.5110110.5Creek Bed Invert (ft)October 1, 2016 May 31, 2019Section 3210.45 - Low Flow Swale Flowline Elevation Change Over Time
18 01002003004005001061081101121141161181201222422.36 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00002422.36Proposed Low Flow SwaleExisting Calle Joaquin Wetland
19 107107.25107.5107.75108108.25108.5Creek Bed Invert (ft)October 1, 2016 May 31, 20192422.36 - Low Flow Swale Flowline Elevation Change Over Time
20 01002003004005006007001061081101121141161181201222031.65 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00002031.65Proposed Low Flow SwaleExisting Calle Joaquin Wetland
21 106.5106.75107107.25107.5107.75108108.25108.5Creek Bed Invert (ft)October 1, 2016 May 31, 20192031.65 - Low Flow Swale Flowline Elevation Change Over Time
22 01002003004005006001021041061081101121141161181201221757.69 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00001757.69Proposed Low Flow SwaleExisting Calle Joaquin WetlandSee "Analysis Results" on Pg. 4
23 102.4102.6102.8103103.2103.4103.6103.8104104.2104.4Creek Bed Invert (ft)October 1, 2016 May 31, 20191757.69 - Low Flow Swale Flowline Elevation Change Over Time
24 01002003004001001051101151201251301351429.43 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 00001429.43Existing CreekProposed HighFlow Bypass
25 102.25102.5102.75103103.25Creek Bed Invert (ft)October 1, 2016 May 31, 2019Section 1429.43 - Low Flow Swale Flowline Elevation Change Over Time
26 010020030040050090100110120130140150160912.75 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 0000912.75Existing CreekHigh Flow Bypass
27 96.2596.596.7597Creek Bed Invert (ft)October 1, 2016 May 31, 2019912.75 - Low Flow Swale Flowline Elevation Change Over Time
28 010020030040050090100110120130140150160603.53 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 0000603.53Proposed DetentionBasinExisting Creek
29 96.296.4596.796.9597.2Creek Bed Invert (ft)October 1, 2016 May 31, 2019603.53 - Low Flow Swale Flowline Elevation Change Over Time
30 010020030040050060070095100105110115120125130463.85 Station (ft)Elevation (ft)Legend01Oct2016 010031May2019 0000463.85Existing CreekProposed DetentionBasin
31 9595.2595.595.7596Creek Bed Invert (ft)October 1, 2016 May 31, 2019463.85 - Low Flow Swale Flowline Elevation Change Over Time