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HomeMy WebLinkAbout07/19/2011, C 15 - SILT REMOVAL - VARIOUS LOCATIONS, SPECIFICATION NO. 91065 � J council July 19,2011 j acEnda PepoRt C I TY O F SAN LU I S O B I S P O FROM: Jay D. Walter, Director of Public Works 9W Prepared By: Dan Van Beveren, Senior Civil Engineer SUBJECT: SILT REMOVAL—VARIOUS LOCATIONS, SPECIFICATION NO. 91065 RECOMMENDATION 1. Approve plans and specifications for Silt Removal —Various Locations, Specification No. 91065. 2. Authorize staff to advertise for bids. 3. Authorize the City Manager to award the contract if the lowest responsible bid is within the Engineer's Estimate of$150,000. 4. Approve the transfer of approved project budget from the Master Silt Removal account to the projects account at time of contract award. DISCUSSION Background The City's creeks contain locations where sediment collects over time and requires removal to facilitate storm flow. This project consists of the removal of accumulated sediment from the following three locations: 1) San Luis Obispo Creek at the Marsh Street Bridge, 2) Prefumo Creek at Los Osos Valley Road, and 3) Prefumo Creek at Madonna Road. Sediment has accumulated in these three locations over the past several years and needs to be removed in order to restore drainage capacity. San Luis Obispo Creek at the Marsh Street Bridge The portion of San Luis Obispo Creek beneath the Marsh Street Bridge is a location where the creek makes a gradual sweeping curve. During periods of heavy flow, sedimentation accumulates along the inside of this curve. As a result, several feet of material has been deposited along the western portion of the creek beneath the bridge. Sediment has routinely been removed from this location every few years in order to maintain the capacity of the creek channel at this critical location, which is prone to flooding during significant storm events. This sediment removal work was last done in 2007. Prefumo Creek at Los Osos Valley Road The portion of Prefumo Creek between Los Osos Valley Road and Laguna Lake is a location where the creek slope flattens and sediment accumulates as the water in the creek slows down prior to entering Laguna Lake. Sedimentation has historically been removed from this location every few years in order to maintain the capacity of the creek channel and to help prevent the accumulated sediment from migrating into the lake. This sediment removal work was last done in 2006. C15-1 o Silt Removal—Various Locations (91065) Page 2 Prefumo Creek at Madonna Road Immediately downstream from Laguna Lake, Prefumo Creek crosses under Madonna Road and continues in a southerly direction. The accumulation of sediment in this location now slows the creek in low flow conditions. Standing water now remains for several weeks following each rain event. The removal of sediment from this location will reduce the problem of standing water and will restore the channel to its previous flow capacity. There are no records of silt removal work previously being done at this location. Regulatory Permitting Due to the location of these projects within the creek system, work must be scheduled for the late summer or early fall - the time of year when the water in the creeks is lowest, and when work can be performed without impacting the flowing water within the creeks. As such, scheduling these projects around this limited construction timeline requires advance planning in both the design effort as well as the anticipated receipt of all necessary regulatory permits. All three of these project locations require regulatory permits from the Army Corps of Engineers, the California Department of Fish and Game and the Califomia Regional Water Quality Control Board. As of July 1, 2011, only the Department of Fish and Game permit has been received, and staff is currently awaiting receipt of the other two permits. The recommended action will allow the project to be advertised now, and then awarded in the event that the necessary permits are received by early September. If the permits are not received within this timeline; the project will have to be postponed until 2012. CONCURRENCES The project is approved by the California Department of Fish and Game through its issuance of the 2008 Streambed Alteration Agreement for routing creek maintenance. The Department has been notified of the project, as required in the 2008 Agreement. A Water Quality Certification from the California Regional Water Quality Control Board and a Letter of Permission from the Army Corps of Engineers are currently pending. The City's Community Development Department is scheduled to issue a Mitigated Negative Declaration for this project during the week of July 11, 2011. Any mitigation measures identified in this environmental document will be incorporated into the project specifications prior to advertisement. FISCAL IMPACT The 2011-13 Financial Plan, Appendix B, page 3-185, identifies $250,000 of construction funding in 2011-12. The source of these budgeted funds is the San Luis Obispo County Flood Control and Water Conservation District Zone 9 program which oversees and provides funding for flood control improvements located within the San Luis Obispo Creek watershed. C15-2 O J Silt Removal-Various Locations (91065) Page 3 The project budget is detailed in the following table. Silt Removal Various Locations-Contruction Costs LConstruction: -----_._ —.__.-.-- ---------.--..__{ $_1502000' IConstruction Conti ngencies: Total for Construction: -- _ { _$165,000 �Mic. Construction Costs (Printing, Materials Testing, Etc.) $5,000 Total Cost of Project — _— _ $17070001 'Available Balance in Silt Removal Master Account --- -----..-. _ --- ----..------..-.---------- — - Funding is currently located in the construction phase of the Silt Removal Master account (90581), which has a balance of$298,900 as of July 1, 2011. Staff recommends transferring funds once the bids are received and the project is awarded. Fiscal Impact Summary Bal. as of 7/1/11 Proposed Change Silt Removal-Various Locations(91065) - 170,000 170,000 Master Silt Removal Account (90581) 298,900 128,900 (170,000) Total 298,900 298,900 - AVAILABLE FOR REVIEW IN THE COUNCIL OFFICE Plans and Special Provisions for Silt Removal-Various Locations, Specification No. 91065. T:\Council Agenda Reports\Public Works CARU.011\CIP\91065 Silt Removal - Various Locations\91065 E-Council Agenda Report - Silt Removal Various Locations.doc C15-3 b council memoizanbum July 11,2011 TO: City Council FROM: Jay D. Walter,Director of Public Works VIA: Katie Lichtig,City Manager K SUBJECT: RED FILE ITEM—Silt Removal Various Locations, Spec. No. 91065 The Council Agenda Report that was included in the Agenda packet for this item did not include a project vicinity map. Please find the attached map. If you have questions,please contact Jay Walter, Director of Public Works. Attachment Vicinity Map—Silt Removal Various Locations, Spec. No 91065 G:\Staff-Reports-Agendas-Minutes\-CCMemos\2011\91065 Red File-Vicinity Map.doc herd cour. Cn1atl: o ODUNCU. a CDD DIR a CrrYMGR a FrTD1R a A98rCM a FIRECHU a ATMPIMY C PWDIR RED FILE a °�O�G a POLIMMEF C3 PB 0PAPM&UCDIR — MEETING AGENDA O 7� a o i$Dm UMIDIt a alawrn+ns o SWCrrYNM acoUWn DA ITEM # ° l a cm MGR a CLERK I + � •■■.■■:i►• �\'�- re - : -3, �iPREFU . ��,��. �- I Imo.. �'c::•1 ^�; �~ 0 MADONNA RW lit LEGEND SILT REMOVAL N c a- w • w � n i PROJECTS j RED FILE MEETING AGENDA From: rschmidt@rain.org[SMTP:RSCHMIDT@RAIN.ORG] /? ! ITEM # Gy�" Sent: Monday, July 18, 2011 10:18:37 AM DAT To: Council, S1oCity Subject: Item C-15 and Broad Street Culvert Needs Help Too Auto forwarded by a Rule Re: Item C-15 and Siltation of Broad Street Culvert Dear Council Members:' I read with interest the staff report on item C-15. which proposes to spend $170, 000 on three silt removal projects, none of which appear to be needed for property protection or life safety. According to the staff report, there is currently approximately $300, 000 in the city's bank account available for silt removal. So my question is why, given the availability of funds, does the city not remove silt from the Broad/Murray Old Garden Creek culvert and its entrance and exit, where flood capacity is badly diminished by the presence of extensive silt buildup? In the case of this culvert, the urgency of action is underwritten by the fact that both property and life safety are endangered by the city's inaction -- this is a flood prone neighborhood, and lack of culvert capacity is the flood cause. I have written about this matter so many times I find it incredible that the city remains obstinate in dealing with the matter. Last time I was told the reason for inaction was financial, but with the current staff report, that clearly is not the real reason, as there's plenty of money for this little silt clearing project. The cost/benefit ratio of this silt removal would be far better than for any of the staff-proposed projects. I've enclosed photos from last fall to refresh your memory. The main difference between then and now is that there's even more silt now than then. I request you direct staff to deal with the Broad/Murray culvert cleaning hard copy: small: this season, before another winter' s storms arrive. a COUNCIL aCOO DIR o CRY MGR o FIT DDR Thank you. o ASST CM a FIRE CHIEF a ATTORNEY o PW DIR o CLERKIORIO a POLICECHIEF Richard Schmidt a PIR aPARKS&RECDDR a TRIBUNE a UTIL DIR a NEWTNES a AR DIR a SLO CRY NEWS o COUNCIL Photo captions Q�GR 1. Exotic weed trees have been allowed to grow up within the creek flow 0 0 area, creating a massive barrier right in front of the culvert exit. The result is a root-infested silt-buildup several feet deep where previously there was year-round creek flow that provided plenty of exit capacity for the culvert. About a decade ago, the city promised regular maintenance to assure proper flood flow around the trees, but like so many city promises, this has not been fulfilled. The previous public works director agreed the trees, with their vigorous root systems and intrusion into the floodway, were the source of the siltation problem. (FYI: The area to the right of the trees, the mass of rubble covered with leaves, was previously part of the creek flow area. Now junk piles up between the flood wall and the trees, and no effort is made to remove it. ) 2. Gravel bar at culvert outlet blocks flow from the culvert. The weed trees are to the left, just beyond the picture border. This pile of gravel and silt needs to be removed for proper function of the culvert in flood times. 3. As a result of obstruction of the culvert exit, silt has backed up into the culvert and fills nearly one third of its depth. 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