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Home My WebLink About04/04/2011, C6 - STORM DRAIN CULVERT REPAIRS, SPECIFICATION NO. 90744 council w"lingD- Aril 5,2011 acEnbA mpout 1W.N.,dw e,& C I TY O F SAN LU I S O B I S P O FROM: Jay D. Walter, Director of Public Works YDW Prepared By: Dan Van Beveren, Senior Civil Engineer SUBJECT: STORM DRAIN CULVERT REPAIRS, SPECIFICATION NO. 90744 RECOMMENDATION 1. Approve plans and specifications for Storm Drain Culvert Repairs, Specification No. 90744. 2. Authorize staff to advertise for bids and authorize the City Manager to award the contract if the lowest responsible bid is within the Engineer's Estimate of$205,000. 3. Approve the use and transfer of$40,900 from the CIP Completed Projects account and$15,000 from the Master Corrugated Metal Pipe (CMP) Replacement account to the Storm Drain Culvert Repairs project account for construction. DISCUSSION Storm Drain Culvert Repairs are included in the 2009-11 Capital Improvement Plan and address the 2009-11 Major City Goal, Infrastructure Maintenance.The Storm Drain_ Culvert Repair project scope consists of repairs to an existing culvert under Higuera Street between Bridge Street and Elks Lane (see attached Vicinity Map). This project will be 100%funded through Measure Y, the half cent sales tax measure approved by the City's residents. The Higuera Street culvert carries stormwater flow from Exposition Creek under Higuera Street and has been in service since 1911. The original structure was essentially a short concrete bridge, and was approximately 20 feet wide by about 15 feet long. As Higuera Street was widened over the years, the culvert was extended to accommodate the widening of the roadway above. Today, the culvert spans approximately 90 feet of City right-of-way; and extends further in both the upstream and downstream directions onto adjacent private properties, and totals approximately 460 feet in length. Only the portion of culvert within the City's right-of-way is included within the scope of work of this project; the portions outside of the City's right-of-way are the responsibility of the respective owners of the adjacent private properties. As stated above, the original structure was essentially a short concrete bridge. This original bridge did not contain a concrete bottom. The subsequent widening of the culvert included the placement of a concrete floor along the extended portion of the culvert, but left the original portion with the culvert floor of exposed soil. The portion of exposed soil has experienced significant scour over time, resulting in prolonged ponding of water and collection of debris in the area of exposed soil. Scope of Work C6-1 Storm Drain Culvert Repairs,Spec No.90744 Page 2 In December 2008, a Structural Condition Assessment Report was prepared by Wallace Group. The report contains a discussion on the current condition of the storm drain culvert and recommends the following specific actions to extend the service life of the culvert. 1. In order to stop the ponding of water, the collection of debris, and the reduction in flow capacity, it is recommended that a concrete floor be placed in the portion where soil is exposed. This improvement would not only reduce the deposition of debris, it would also prevent further scour and damage to the adjacent concrete surfaces as well as increase the flow carrying capacity of the structure. 2. Portions of the structure's sides include penetrations where existing adjacent surface drains connect to the culvert. In these areas, concrete has spalled, rusted, and worn to the point where the concrete is weakened and rebar is exposed. The scope of work includes repairs in these isolated areas through concrete patching and replacement of rebar. 3. A portion of the culvert roof is of specific concern; the concrete has spalled and worn to a point where there is potential for this culvert roof to worsen and eventually collapse. The scope of work includes the replacement of this portion of the culvert with a new reinforced concrete roof which has been structurally designed to support the roadway above. In addition to the three specific work scope items discussed above, the project scope also includes the lining of adjacent CMP storm drains which connect to the culvert. Due to ongoing maintenance needs of CMP storm drains citywide, it has been judged to be cost effective to line these existing CMP storm drains with modem plastic liners in order to reduce corrosion and extend the service life of these structures. CONCURRENCES The California Department of Fish and Game has issued a Streambed Alteration Agreement for the proposed work. The agreement requires the work to be conducted during the summer months when the culvert does not typically carry any stormwater flow. The City's Community Development Department has filed a Categorical Exemption per the requirements of the California Environmental Equality Act (CEQA). The Categorical Exemption has been granted based on the project scope consisting of maintenance of an existing facility. FISCAL IMPACT The project is identified in the 2009-11 Financial Plan, page 3-243, with a preliminary cost estimate of $150,000. With the plans now complete, the updated Engineer's Estimate of construction costs is $205,000. This project will be 100% funded through Measure Y, the half-cent sales tax measure approved by the City's residents. C6-2 1 Storm Drain Culvert Repairs,Spec No.90744 Page 3 Storm Drain Culvert Repairs -Construction Costs Construction: $205,0001 Construction Contingencies: 1$$41,0 0000 Total for Construction: 1 $246,0001 Printing & Materials Testing �__. $12,500] I f Total Cost $258,5001 Construction contingency funding of$41,000 is requested to complete this work. This project will complete work on a deteriorated culvert on a highly traveled street. The likelihood of unknown issues that will need to be addressed quickly to reduce public inconvenience of this work is large. The Storm Drain Culvert Repairs account currently contains a balance of $202,600. The recommended action will utilize $40,900 which is available in the CIP Completed Projects account and $15,000 which is available in the Master CMP Replacement account. current proposed change Funding Sources Master CMP Replacement Account(90742) $183,500 $168,500 415,000 CII'Completed Projects Account(99899) $41,000 $100 -$40,900 Project Account Storm Drain Culvert Repairs(90744) 1 $202,6001 $258,5001 $55,900 Total I I I $0 At the time that the construction contract is awarded, staff will evaluate the availability of in-house resources and determine whether or not a consultant firm will be needed to assist with the construction management. ATTACHMENT Vicinity Map AVAILABLE FOR REVIEW IN THE COUNCIL OFFICE 1. Plans and Special Provisions for the Storm Drain Culvert Repair Project 2. Structural Condition Assessment Report by Wallace Group T:\Council Agenda Reports\Public Works CAR\2011\CIP\90744 Storm Drain Culvert Repiars\90744 CAR Advertise.doc C6-3 ATTACHMENT' FrsouTH W cr LU r, Q T— Y C/-) 0� BRIDGE hl�ll�Ill,'I' �w o 400' 800' 1 INCH Zoo FEET V Clay Or STORM DRAIN CULVERT REPAIRS San LUIS OB1Sp0 . VICINITY MAP C6-4