HomeMy WebLinkAbout05/17/2011, B 3 - WATER RECLAMATION FACILITY MASTER PLAN council
j acEnba Repoin
CITY OF SAN LUIS OBISPO
FROM: Came Mattingly, Utilities Directo �
Prepared By: David Hix Wastewater Division Manage
SUBJECT: WATER RECLAMATION FACILITY MASTER PLAN
RECOMMENDATION
Receive and file report.
REPORT IN BRIEF
The contract for the Water Reclamation Facility (WRF) Master Plan was approved in January
2003 to address specific WRF improvements that are indentified in the 2000 Wastewater Master
Plan. These improvements are related to additional capacity to serve the Margarita, Airport, and
Orcutt specific areas, known deficiencies of existing infrastructure, and treatment improvements
needed to meet more stringent proposed regulatory discharge requirements. The final report
provides planning level analysis and costs for these anticipated upgrades.
The Master Plan presents recommendations and alternatives to meeting the discharge
requirements driven by the Municipal and Domestic (MUN) beneficial use of San Luis Obispo
Creek. These regulations will require additional treatment levels, specifically for reducing
nutrients and trihalomethanes (THMs). The plan also provides an alternative if the proposed
discharge regulations are not required. Considerations for operational efficiency and flexibility,
green house gases, and water reuse are incorporated into the recommendations.
Design and construction of upgrades at the WRF have been postponed due to on-going regulatory
discussions and negotiations concerning the MUN use and minimal increases in flows to the
facility that would create capacity concerns. This will allow continuing study and analysis of the
best alternatives when design begins sometime in the future.
The master plan is a guidance document that will assist the City in identifying the community's
future needs related to the treatment of its wastewater.
DISCUSSION
Background
In October 2000 the Wastewater Master Plan was completed to address the needed capacity and
infrastructure identified in the Margarita, Airport, and Orcutt specific plans. The Master Plan
identifies and recommends WRF and wastewater collection system improvements needed to
correct known deficiencies and anticipated growth per the City's General Plan. The Master Plan
provides adequate detail for future collection system improvements, but the WRF
recommendations require an additional, more detailed study and analysis.
B3-1
Water Reclamation Facility Master Plan Page 2
To address the recommendations in the Wastewater Master Plan, the City Council approved an
RFP for analysis and design services for the WRF, also known as the WRF Master Plan, in
September of 2002. On January 30, 2003, Council approved a contract with Brown and Caldwell
to study and analyze three major components:
1. Capacity for expansion and the addition of processes required for the City's future growth.
2. Infrastructure deficiencies and/or needed improvements to enhance operational
efficiencies.
3. Treatment improvements to meet proposed regulatory discharge requirements.
Since 2003, the City has been working diligently on studies to determine if the level of treatment
required by the Regional Water Quality Control Board (RWQCB) is appropriate for San Luis
Obispo Creek. The discharge requirements to meet the Municipal and Domestic (MUN)beneficial
use of San Luis Obispo Creek are a driver for significant costs associated with upgrading the
treatment processes. Currently the WRF meets all of the beneficial use requirements for San Luis
Obispo Creek except for Municipal and Domestic (MUN).
In 2007, the RWQCB administratively extended the WRF's National Pollutant Discharge
Elimination System (NPDES) permit until the MUN issue is resolved. Because the outcome of the
MUN issue was unknown, Council approved an update to the plan in April 2008 to analyze 1)
alternatives to process upgrades if the creek is dedesignated, 2) analysis of existing and aged
processes, and 3) a detailed cost breakdown to complete the plan in a manner that will be useful
for either scenario.
The WRF Master Plan provides planning level analysis and cost estimates to meet the anticipated
needs facing the City in the future. The plan provides a conservative estimate of upgrades and cost
and will be used as a guide when making decisions regarding the design of the WRF upgrade.
The WRF
The City's wastewater treatment plant has been treating wastewater since the 1920's and
discharging to San Luis Obispo Creek since the 1940's. Periodic upgrades have been required with
the last upgrade completed in 1994. The 1994 upgrade cost $25 million and resulted in the
construction of a tertiary treatment facility that removes ammonia, provides filtration and cooling,
and disinfects and de-chlorinates before discharge to San Luis Obispo Creek. The upgrade also
replaced some aging processes. These improvements met the creek's freshwater habitat
requirements and have resulted in the return of many species, most notably steelhead trout.
The WRF's high level of water quality requires very little additional treatment to meet the State's
recycled water criteria. The WRF currently produces approximately 160 acre feet of recycled
water every year that is used on the City's parks and golf course along with Laguna Middle School
and several commercial businesses.
B3-2
Water Reclamation Facility Master Plan Page 3
Because the MUN beneficial use was placed into the WRF's NPDES permit after design and
financing of the WRF upgrade had been completed, the 1994 WRF upgrade did not include
processes that met the MUN criteria.
The WRF currently treats approximately 4.5 million gallons per day (MGD) of used water with a
capacity of 5.1 MGD.
Nitrate and Trihalomethane Treatment
The proposed NPDES permit discharge requirements require the reduction of nitrate and
trihalomethane (THMs) concentrations currently being discharged. The reduction of nitrate and
THMs to meet the MUN use are the most expensive aspects of the WRF Master Plan. Nitrates are
the product of the conversion of ammonia to nitrate and THMs are produced by the interaction of
organic matter in wastewater with chlorine used for disinfection. The proposed nitrate limit of 10
mg/L is approximately 2.5 to 3 times lower than the existing discharge while the THM limit is 24
to 52 times lower.
Nitrate removal is a biological process that utilizes a specific collection of organisms that convert
ammonia to nitrates and nitrates to nitrogen gas. This is an additional level of treatment to what
the WRF currently treats to. There are several proven denitrification processes that the Master
Plan analyzed based on the ability to meet a 10 mg/L nitrate limit for which construction and
operating cost estimates are included. The report identifies the Modified Ludzack-Ettinger (MLE)
process as the best alternative for the City. The Master Plan finds that MLE allows for the most
flexible operations during the higher flows the WRF experiences during wet weather. Alternatives
will be thoroughly reviewed prior to design to ensure the selection of the most effective process.
Section 7 of the WRF master plan provides an in-depth analysis of denitrification processes.
THM treatment would require a different process than the current use of sodium hypochlorite
(chlorine) for disinfection. To achieve the proposed THM limit, a substitute for chlorine must be
used. Presently, ultraviolet disinfection (UV) is a common alternative to chlorine. Because of the
cost of UV, the City requested a disinfection study in WRF's current National Pollutant Discharge
Elimination System (NPDES) permit to determine other alternatives. A pilot study utilizing
chlorine dioxide was completed in 2009 to determine if this process could meet the proposed
THM limit without major modification of the current disinfection facility at the WRF. The pilot
study determined that chlorine dioxide is a viable alternative and it is currently the recommended
disinfection alternative in the Master Plan, although not currently being used at any other
wastewater treatment facility at this time in the nation. The Master Plan provides a thorough
analysis of disinfection alternatives in section 8.
Wet Weather Operations
During wet weather, the collection system experiences high flows caused by inflow and
infiltration (I&I) of rainwater. These high flows result in the WRF peaking at 4 times its normal
flow, approximately 20 MGD or greater. The WRF is allowed to split its flow around its current
nitrification process and filtration before disinfection and discharge to the creek. This preserves
the sensitive biological nitrification process, while meeting all of the discharge requirements.
B3-3
I
Water Reclamation Facility Master Plan Page 4
If the WRF is unable to treat flows in this manner in the future, then processes will be required to
be significantly enlarged to treat all of the wet weather flows through each process. This will add
additional expense to several processes, such as denitrification and disinfection, for short lived and
infrequent high flows. Additional piping, control equipment, and other ancillary equipment may
also be required. City staff is currently finalizing a study to determine the best strategy to control
I&I and will be returning to Council with the results. City staff will pursue preserving the current
split flow operation with the RWQCB when the WRF's permit is revised in the future. Section 3
of the WRF Master Plan provides a discussion of the WRF flowsandprocess sizing.
Capacity
Section 3 of the Master Plan provides a detailed analysis of the WRF's future flows and loadings
based upon anticipated population growth to the year 2030. Because of the relatively slow growth
rate of the City, population trends have been difficult to predict and model. This has resulted in
population assumptions from 49,675 to 55,247 and flows ranging from 5.29 MGD to 5.83 MGD
being examined in the Master Plan. Past growth assumptions predicted capacity would be
exceeded by this time, while in reality flows have seen only minor increases. Analysis of current
growth rates, anticipated Cal Poly growth, and growth allowed under the updated Land Use
Element, policy 1.10.02, were all considered when determining future flows and process sizing.
This is a critical element that influences WRF design. Population growth will be closely
monitored to ensure the design and construction process begins in an appropriate time frame.
Infrastructure
Several processes and some equipment at the WRF have been in service well past expected
lifespans and some of these items may not work within the new treatment processes. The Master
Plan has studied what infrastructure may require updating or may not be able to continue in
service because of inefficiencies or incompatibility with the proposed updated facility.
Additional processes have also been identified to add reliability. The WRF has several processes
that have no redundancy, making operations difficult during maintenance or equipment failure.
Section 4 of the Master Plan details and analyzes the WRF's existing processes and equipment.
Efficiency,Greenhouse Gases, and Water Reuse
Consideration of ongoing operations and maintenance of the WRF is a critical component to the
analysis and planning of its design. Because the majority of costs in treating wastewater are fixed,
efficient operations and maintenance is a key area where the City can control costs. Energy
conservation is a driver behind the recommended alternatives. These alternatives were evaluated
to determine greenhouse gas emissions and their impacts. Proper steps will be taken to ensure that
the recommended processes and their operations will meet all State and Federal climate change
requirements and the City's energy, sustainability, and climate change goals.
The Master Plan analyzed recycled water production to make certain adequate capacity and
operational flexibility were considered during the study. These will be achieved through many of
the needed capacity upgrades, and were considered in the selection of many other process
recommendations. This will allow the maximization of recycled water production while
minimizing energy usage during normal operations.
B3-4
Water Reclamation Facility Master Plan Page 5
Like population and flow assumptions, process recommendations will be fully evaluated for
energy and greenhouse gas impacts, and incorporated into the final design assumptions. Section 11
of the Mater Plan provides discussion on greenhouse gas analysis.
When Do We Start?
The administrative extension of the WRF's permit and relatively little change in flows to the WRF
has allowed the extended operation of the present facility. This has provided time for additional
studies to analyze the MUN issues and brought the City closer to the retirement of the debt service
from the 1994 upgrade, which will be paid off two years from now. The extension has also
allowed for the ongoing study of flow and population trends.
It is difficult to predict exactly when the WRF will require upgrading, but it is currently projected
for 2015. Staff will be closely monitoring population, flow, growth, and the on-going regulatory
process in order to make a recommendation when design should begin. Many important decisions
regarding the MUN beneficial use of San Luis Obispo Creek will likely occur in the next 12 to 18
months. Staff will periodically bring Council updates on the dedesignation process.
Currently, with very slow growth and no appreciable increase in flow, the WRF may have several
more years of operation before reaching capacity. This point may be made moot by the revision of
the WRF's NPDES permit, which would give the City five years to have processes in place to
meet the MUN requirements. Staff will be closely monitoring both the capacity and continuing
regulatory discussion to ensure that the WRF design meets the appropriate regulatory requirements
and the future needs of the community.
California Environmental Quality Act
This planning study is statutorily exempt under Section 15262 of the CEQA Guidelines. Required
additional levels of environmental review will be performed during design phase prior to
construction of the WRF upgrade.
Summary
The WRF Master Plan is a planning document and guide for the future upgrade of the WRF. Many
of the planning numbers are conservative to provide good recommendations at this level of study.
During the period of time between study and design, it may be decided that some portions of the
plan may not need to be implemented or that portions may be completed through the City's capital
improvement program. Some of these decisions can be made using the Master Plan as a guide, `
while others will be made during the future design process. The goal will be to reduce costs while
allowing for the most efficient design.
The WRF Master Plan provides the City with information that assists it in making decisions about
the future. Regulatory requirements and capacity will be the biggest drivers as to what is built and
when the WRF upgrade begins. The Master Plan is one of the tools that will help determine the
best course for the WRF upgrade and what will best meet the needs of the community.
B3-5
Water Reclamation Facility Master Plan Page 6
FISCAL IMPACT
There is no fiscal impact associated with this report. Completing the WRF Master Plan cost
$320,000. Chapter 12 of the Master Plan provides a breakdown of the costs associated with the
upgrade. All costs are planning level costs, conservative, and do not provide a specific level of
detail, such as design cost estimates or more inclusive construction estimates. If San Luis Obispo
Creek is dedesignated for the MUN beneficial use, then a smaller cost for the upgrade is
anticipated. Staff has provided an estimate based upon the Master Plan, discussions with the
consultant, and operating knowledge of the WRF.
Development is anticipated to pay for a portion of the WRF upgrade. Capacity upgrades or costs
associated with meeting future growth will be assigned to new development. Upgrades to meet
regulatory requirements and infrastructure needs will be shared amongst the entire community.
Sewer rates are being incrementally increased to support the estimated debt service for the plant
construction projected to commence in 2015. Staff is pursuing alternatives to reduce costs
associated with the plant upgrade.
Optional recommendations were presented in the report and represented costs that showed little
long term benefit. These were not included in staff's estimate of costs. As an example; improving
biosolids treatment to Exceptional Quality (EQ) requires significant capital costs with the solids 1.
still having to be hauled off site. Hauling costs are comparable to what the City pays now for
hauling with current treatment levels.
The 2011-13 Financial Plan proposes a capital improvement request for the WRF upgrade of
$64,300,600 with design beginning in 2012-13 and construction in 2014-15. These dates may be
changed due to on-going regulatory negotiations and population/flow monitoring. The capital
improvement request does not include every recommendation in the Master Plan. Staff believes
that the fimding requested in the Financial Plan provides a responsible cost estimate for the future
WRF upgrade.
Table 1. Future Design and Construction Activities
Activity Implementation Date Completion Estimate
Design and Construction Managemen Winter 2013 Summer $8,000,00
of Upgraded WRF 2014
Construction of Upgraded WRF Spring 2015 Fall 2017 *$56,300,00
to $36,840,00
Total *$64,300,60
to $44,300,00
*This range is the difference between upgrades required for adding processes to meet MUN and meeting current
permit requirements. It has been estimated to be approximately$20 million.
Council Reading File: Water Reclamation Facility Master Plan
B3-6