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HomeMy WebLinkAboutStaff Report 5.B 11/07/2016DATE: November 7, 2016 Agenda Item #5.B TO: Honorable Mayor and Members of the City Council through City Manager FROM: Dan St. John, F.ASCE — Director, Public Works & Utilities Larry Zimmer, P.E. — Deputy Director, Public Works & Utilities SUBJECT: Resolution Authorizing the City Manager to Execute a Cooperative Agreement with Caltrans to Complete a Water Quality Mitigation Project along Old Corona Road RECOMMENDATION It is recommended that the City Council adopt the attached Resolution Authorizing the City Manager to Execute a Cooperative Agreement with Caltrans to Complete a Water Quality Mitigation Project along Old Corona Road. BACKGROUND The proposed mitigation project supports Caltrans' effort to upgrade U.S. Highway 101 between Novato and Petaluma as part of the Marin- Sonoma Narrows HOV Widening Project (MSN). Caltrans has divided the overall MSN project into six individual contracts. One of which is the MSN Segment B3, which starts approximately one -half mile south of San Antonio Creek in Marin County and ends at Kastania Road in Sonoma County. This project phase consists of realigning the highway to correct substandard horizontal curves; re- profiling the highway to correct substandard vertical curve sight distance; reducing flood hazard by building a new San Antonio Creek Bridge at a higher profile to raise it out of the floodplain; and, removing direct vehicle access to the highway by constructing new frontage roads and converting the existing northbound lanes to a frontage road once the new lanes are in place. This project resulted in environmental impacts, most of which are being mitigated by Caltrans. However, new impervious pavement as part of MSN B3 resulted in additional roadway pollutants, which requires "off- site" mitigation due to inadequate right -of -way within the 101 corridor. Consequently, Caltrans requested the assistance of the City of Petaluma to provide an off -site location that can treat stormwater run -off from 7.19 acres of highway surface within the Petaluma River watershed. The proposed co -op agreement addresses this need by placing the project within City right -of -way and provides adequate funding to the City to build and maintain the project. DISCUSSION The proposed project will improve the water filtration and hydraulic carrying capacity of an existing roadside open ditch adjacent to Old Corona Road of approximately 25 to 30 feet in width for a distance of 550 linear feet. Downstream of the roadside ditch, flow will be diverted to two bio- retention basins for further water quality improvement prior to discharge to the Petaluma River. The roadside ditch, once modified, will treat highway runoff from twin box culverts carrying Highway 101 runoff from north of the Corona Road overcrossing, flows from the open ditch running parallel to the west edge of Highway 101, and runoff from the rear edge of an adjacent new and used auto sales lot. The existing ditch currently has limited wetland or filtration value, but can be expanded to 13,000 to 16,000 square feet of planted wetland of improved filtration capacity. Existing biotic value will be preserved, while the remaining portions of the ditch will be widened, ornamental and invasive plant species removed, and appropriate vegetation replanted. At the downstream end of the improved channel, an inlet will capture low flows, and divert it through twin outfalls into two bio - retention basins, totaling approximately 30,000 square feet. These basins will be created within the upland area of an existing flood terrace along the Denman Reach of the Petaluma River Upon execution of the cooperative agreement, staff will solicit proposals to design the project. The design consultant will also be responsible for the environmental documention per CEQA. The project will come back to Council to approve the environmental document and for award of the contruction contract prior to beginning construction. Construction is expected in FY 17/18. FINANCIAL IMPACTS The total cost of constructing the project and performing the necessary maintenance for a period of no less than twenty (20) years is estimated to not exceed $1,379,000. All costs associated with this work will be reimbursed by Caltrans and will be reflected in the FY 17/18 budget proposal. ATTACHMENTS 1. Resolution 2. Location Map 3. Agreement 2 Attachment 1 RESOLUTION AUTHORIZING THE CITY MANAGER TO EXECUTE A COOPERATIVE AGREEMENT WITH CALTRANS TO COMPLETE A WATER QUALITY MITIGATION PROJECT ALONG OLD CORONA ROAD WHEREAS, Caltrans is upgrading U.S. Highway 101 between Novato and Petaluma as part of the Marin- Sonoma Narrows HOV Widening Project; and WHEREAS, due to inadequate right of way within the 101 corridor, Caltrans has requested the assistance of the City of Petaluma to provide an off -site location that treats stormwater run -off from an equivalent 7.19 acres of highway surface within the Petaluma River watershed; and WHEREAS, the City desires to assist Caltrans by implementing the Old Corona Road Water Quality Mitigation Project; and WHEREAS, all funding for project shall be reimbursed in fall by Caltrans; and WHEREAS, staff shall oversee design and construction of project; and WHEREAS, City and Caltrans agree to enter into a cooperative agreement. NOW, THEREFORE, BE IT RESOLVED that the City Council of the City of Petaluma hereby authorizes and directs the City Manager to execute the attached Cooperative Agreement with Caltrans to treat an equivalent 7.19 acres of highway surface within the Petaluma River watershed. 3 OLD CORONA ROAD WATER QUALITY MITIGATION 'u I I �. \ Z. L 1' \ LOCATION MAP J J °P� J /1 Attachmemt 2 �J J r Date : November 7, 2016 N City of Petaluma a� _� � y PROJECT SITE \� E Public Works and Utilities s Department 4 Attachment 3 Draft 9 -21 -16 (AH) 04 -MRN 101 PM 27.0/27.6 04 -SON 101 PM 0.0/4.5 MSN B3 Off -site Stormwater Treatment 04- 26409/ 0400000735 District Agreement No. 4 -2557 COOPERATIVE AGREEMENT THIS AGREEMENT, ENTERED INTO EFFECTIVE on , 2016, is between the STATE OF CALIFORNIA, acting by and through its Department of Transportation, referred to herein as " CALTRANS," and the CITY OF PETALUMA, a municipal corporation of the referred to herein as "CITY." RECITALS body politic and a State of California, CALTRANS and CITY, hereinafter referred to as "PARTIES," pursuant to Streets and Highways Code sections 114 and /or 130, are authorized to enter into this Agreement. 2. CALTRANS is constructing the U.S. 101 Marin/S onoma Narrows High Occupancy Vehicle (HOV) Widening Contract B3 project in Sonoma County, referred to herein as "PROJECT." 3. PROJECT resulted in the addition of 33.80 acres of added or reworked impervious surface within the jurisdictional boundaries of the State Water Resources Control Board's Region 2, referred to herein as "IMPACTS." 4. The State Water Resources Control Board's Region 2, referred to herein as "WRCB ", issued to CALTRANS a 401 Certification (CIWQS Place No. 797380), dated January 30, 2014, for PROJECT, referred to herein as "401" and incorporated herein by this reference. 26.32 acres will be mitigated by Caltrans construction project (MSN Contract B3 — Caltrans EA 04- 264091) and 0.29 acres will be mitigated by using the surplus 0.29 acres from MSN Contract B I. This co -op addresses the difference of 7.19 acres. As partial mitigation for IMPACTS, Additional Condition 1 of 401 requires that CALTRANS provide an off -site location that treats stormwater run -off from an equivalent 7.19 acres of highway surface within the Petaluma River watershed, referred to herein as "MITIGATION PROJECT ". The location of the proposed off -site stormwater treatment is shown in Exhibit C, attached herewith and made a part of this Agreement. 5 District Agreement No. 4 -2557 5. CITY desires to assist CALTRANS by implementing MITIGATION PROJECT as set forth in this Agreement and further described in Exhibit A, attached hereto and made a part of this Agreement. CITY will also perform any and all required maintenance on the installed MITIGATION PROJECT for a period of no less than twenty (20) years, subject to CALTRANS providing the necessary funding for such maintenance pursuant to this Agreement. CALTRANS will keep maintenance records of the stormwater treatment system. 6. PARTIES have determined that the total cost of constructing MITIGATION PROJECT and performing the necessary maintenance for a period of no less than twenty (20) years is $1,379,000 as detailed in Exhibit B, attached herewith and made a part of this Agreement. All cost increases are subject to, and will be addressed by, mutual agreement. Either party may terminate this Agreement, if mutual agreement cannot be reached. In case of such termination, reasonable costs of winding down the MITIGATION PROJECT work, including payment of non - cancellable obligations to contractors and suppliers, demobilization costs and site closure costs, will be MITIGATION PROJECT costs. 7. The terms of this Agreement shall supersede any inconsistent terms of any prior Memorandum of Understanding (MOU) or agreement relating to PROJECT. 8. PARTIES now define herein below the terms and conditions under which this Agreement will be implemented. SECTION I CITY AGREES: 1. All work performed by CITY, or performed on CITY's behalf, shall be performed in accordance with all state and federal laws, regulations, policies, procedures, and standards. 2. To implement MITIGATION PROJECT as described in Exhibit A, attached hereto and made a part of this Agreement. In the event that a subsequent amendment or modification of Additional Condition 1 of 401 by the WRCB results in additional work not covered by this Agreement (referred to herein as "ADDITIONAL WORK "), this Agreement will be amended to include the completion of ADDITIONAL WORK as well as any additional funding required for the completion of said ADDITIONAL WORK by signed agreement of both parties. 3. To perform all necessary maintenance as described in Exhibit A on the completed MITIGATION PROJECT facilities, currently on CITY's right of way, for a period of no less than twenty (20) years. Thereafter, MITIGATION PROJECT facilities shall be retained as part of CITY's inventory. 4. CITY shall submit an annual maintenance report in electronic format on the Bioretention Unit to CALTRANS by October 1St each year for twenty (20) years as described in Exhibit A. I District Agreement No. 4 -2557 5. To submit one invoice to CALTRANS within thirty (30) calendar days of execution of this Agreement in the amount of $100,000, which represents the initial deposit for work performed pursuant to this Agreement. To submit, thereafter, to CALTRANS itemized invoices monthly and in arrears for costs incurred for work performed related to MITIGATION PROJECT. Total invoices submitted (including the initial deposit) shall not exceed the total amount of $1,379,000 as set forth in Exhibit B unless this Agreement is first amended by agreement of the parties. Said invoices will meet format and content requirements specified by CALTRANS and shall be submitted to the CALTRANS Project Manager for approval and forwarding to the appropriate Accounting Office for payment. 6. Within thirty (30) days of receipt of STATE'S first payment of $100,000, to submit written verification that CITY has deposited $40,000 of that sum into an interest bearing account. Said $40,000 shall be used by CITY to perform any and all required maintenance activities on the completed MITIGATION PROJECT facilities. CITY further agrees to deposit any of CALTRANS' funds that are not utilized to construct PROJECT into said interest bearing account and to utilize said funds for maintenance activities only. 7. To use one hundred percent (100 %) of CALTRANS' funds provided pursuant to this Agreement, in order to satisfy CITY's obligation and responsibilities set forth in this Agreement. If work performed under this Agreement is done under contract (not completed by CITY's own employees) and is governed by the California Labor Code's definition of a "public work" (section 1720(a)(a)), CITY will conform to sections 1720 —1815 of the California Labor Code and all applicable regulations and coverage determinations issued by the Director of Industrial Relations. 9. To include wage requirements in all contracts for "public work" and will require their contractors and consultants to include prevailing wage requirements in all Agreement - funded subcontracts for "public work." 10. To use all of CALTRANS' funds, including any interest accrued thereon, only on MITIGATION PROJECT work specified in Exhibit A. 11. To notify CALTRANS in writing five (5) days prior to the construction start date of MITIGATION PROJECT. 12. To notify CALTRANS in writing and obtain CALTRANS' concurrence prior to making changes to MITIGATION PROJECT, including changes that may affect the location of said MITIGATION PROJECT. 13. To submit written notification to CALTRANS when MITIGATION PROJECT construction has been completed. 14. To retain all books, documents, papers, accounting records, and other evidence pertaining to costs incurred, including support data for cost proposals, and to make such materials available at the respective offices of CALTRANS at all reasonable times for three (3) years 7 District Agreement No. 4 -2557 after the termination date of this Agreement. CALTRANS, the Federal Highway Administration, or any duly authorized representative of the Federal Government shall have access to any books, records, and documents of CITY that are pertinent to this Agreement for audits, examinations, excerpts, and transactions, and copies thereof shall be furnished when requested. SECTION II CALTRANS AGREES: 1. To provide CITY with a copy of 401 and to subsequently notify and provide copies of all subsequent amendments thereto, or correspondence, if any, which may affect MITIGATION PROJECT or maintenance thereof. However, no amendments to the 401 will become amendments to the MITIGATION PROJECT unless and until this Agreement is amended in accordance with the provisions of Section III herein. 2. To deposit with CITY within thirty (30) calendar days of receipt of CITY's signed invoice, the amount of $100,000 for the first invoice and thereafter to deposit with CITY within thirty (30) calendar days after receipt of each subsequent monthly invoice sufficient funds to satisfy each monthly invoice. The monthly invoice will exclude any annual maintenance cost, but will include all approved actual costs incurred for work performed related to the construction of MITIGATION PROJECT. Annual maintenance cost shall be invoiced as one single invoice in the amount of $225,000 upon completion of construction. The total amount of all of the invoices, including that for the initial deposit and annual maintenance cost, will not exceed $1,379,000, which amount represents CALTRANS' total financial obligation as set forth in this Agreement. Upon receipt of all MITIGATION PROJECT reports, plans, and other documents submitted by CITY, CALTRANS will review, comment, approve and forward, if applicable, to State Water Resources Control Board for approval. 3. To issue at no cost to CITY an encroachment permit for the term of this Agreement to permit the CITY and /or the CITY's contractors to enter and construct improvements in and carry out maintenance of the MITIGATION PROJECT within the State Highway System (SHS) right of way. SECTION III IT IS MUTUALLY AGREED: 1. All obligations of CALTRANS under the terms of this Agreement are subject to the appropriation of resources by the Legislature, State Budget Act authority, and the allocation of funds by the California Transportation Commission (CTC). All obligations of CITY under the terms of this Agreement are subject to and conditioned on reimbursements and continued funding from CALTRANS for the cost of performance of the MITIGATION PROJECT, as specified elsewhere in Section II of this Agreement. District Agreement No. 4 -2557 2. All applicable laws, rules and policies relating to the use of federal or state funds shall apply notwithstanding other provisions of this Agreement. CITY shall allow representatives of CALTRANS access to the location of the MITIGATION PROJECT located outside of State Highway System (SHS) right of way for the purpose of verification and monitoring of performance of MITIGATION PROJECT and maintenance thereof. 4. CITY agrees to ensure that after MITIGATION PROJECT is constructed, the installed facilities will be maintained, operated, and managed to all applicable CITY and CALTRANS standards. CITY will submit a maintenance /operation/management standard for CALTRANS' review prior to construction of the stormwater treatment system. 5. The party that discovers hazardous material (HM) will immediately notify the other party to this Agreement. HM -1 is defined as hazardous material (including but not limited to hazardous waste) that may require removal and disposal pursuant to federal or state law, whether it is disturbed by MITIGATION PROJECT or not. HM -2 is defined as hazardous material (including but not limited to hazardous waste) that may require removal and disposal pursuant to federal or state law, only if disturbed by MITIGATION PROJECT. HM management activities associated with either HM -1 or HM -2 include, without limitation, any necessary manifest requirements and designation of disposal facility. 6. CALTRANS, independent of MITIGATION PROJECT, is responsible for any HM -1 found within the existing SHS right of way. CALTRANS will undertake, or cause to be undertaken, HM management activities related to HM -1 with minimum impact to PROJECT schedule and will pay or cause to be paid all costs associated with HM management activities related to HM -1. 7. CALTRANS has no responsibility for management activities or costs associated with HM- 1 found outside the existing SHS right of way. If HM -1 is found outside existing SHS right of way, under state and federal law responsibility for such HM -1 rests with the owner(s) of the parcel(s) on which the HM -1 is found. If HM -1 is found outside the existing SHS right of way, parties will reassess the feasibility of the MITIGATION PROJECT and mutually agree on a course of action prior to the commencement of any additional work. CITY is responsible for the management of any HM -2 found within MITIGATION PROJECT limits. CITY may use up to 5% of the funds already obligated by CALTRANS under this agreement for the costs associated with HM -2 management activities. However, CALTRANS is not responsible to pay any additional money to CITY for these costs. N District Agreement No. 4 -2557 9. CALTRANS' acquisition of or acceptance of title to any property on which any hazardous material is found will proceed in accordance with CALTRANS' policy on such acquisition. 10. In the event that MITIGATION PROJECT facilities are affected by a future CALTRANS or CITY project, the agency responsible for said project shall replace the affected portion of MITIGATION PROJECT facilities at no cost to the other party. Any and all required maintenance of replacement facilities will be completed by CITY with the funding described in Section I, Article 5 of this Agreement. Any additional costs the CITY incurs for maintenance due to portions of the MITIGATION PROJECT facilities affected by a future CALTRANS project will be MITIGATION PROJECT costs. 11. Nothing within the provisions of this Agreement is intended to create duties or obligations to or rights in third parties not a party to this Agreement or to affect the legal liability of either party to the Agreement by imposing any standard of care with respect to the development, design, construction, operation, or maintenance of the SHS and public facilities different from the standard of care imposed by law. 12. Neither CITY nor any officer or employee thereof is responsible for any injury, damage, or liability occurring by reason of anything done or omitted to be done by CALTRANS and /or its agents or contractors under or in connection with any work, authority, or jurisdiction conferred upon CALTRANS under this Agreement. It is understood and agreed that CALTRANS will fully defend, indemnify, and save harmless CITY and all of its officials, officers and employees from all claims, suits, or actions of every name, kind, and description brought forth under, but not limited to, tortious, contractual, inverse condemnation, or other theories or assertions of liability occurring by reason of anything done or omitted to be done by CALTRANS and /or its agents or contractors under this Agreement. 13. Neither CALTRANS nor any officer or employee thereof is responsible for any injury, damage, or liability occurring by reason of anything done or omitted to be done by CITY and /or its agents or contractors under or in connection with any work, authority, or jurisdiction conferred upon CITY under this Agreement. It is understood and agreed that CITY will fully defend, indemnify, and save harmless CALTRANS and all of its officials, officers and employees from all claims, suits, or actions of every name, kind, and description brought forth under, but not limited to, tortious, contractual, inverse condemnation, or other theories or assertions of liability occurring by reason of anything done or omitted to be done by CITY and /or its agents or contractors under this Agreement. 14. No alteration or variation of the terms of this Agreement shall be valid unless made by a formal amendment executed by the PARTIES hereto and no oral understanding or agreement not incorporated herein shall be binding on any of the PARTIES hereto. 15. This Agreement shall terminate upon satisfactory completion of MITIGATION PROJECT or December 31, 2036, whichever comes first. However all indemnification, document retention, audit, claims, environmental, legal challenge, hazardous material, operation, maintenance, and ownership articles will remain in effect until terminated or modified in writing by mutual agreement. 10 SIGNATURES PARTIES declare that: District Agreement No. 4 -2557 1. Each PARTY is an authorized legal entity under federal law and /or California state law. 2. Each PARTY has the authority to enter into this Agreement. 3. The people signing this Agreement have the authority to do so on behalf of their public agencies. STATE OF CALIFORNIA Department of Transportation By: Deputy District Director Approved as to form and procedure: Brandon Reeves Deputy Attorney Department of Transportation Certified as to budgeting of funds: District Budget Manager Certified as to financial terms and conditions: Accounting Administrator CITY OF PETALUMA By: City Manager Approved as to form: Attorney 11 District Agreement No. 4 -2557 EXHIBIT A SCOPE OF WORK This Scope of Work outlines the specific areas of responsibility for completion of the Bioretention Unit project within the CITY's right of way, which includes environmental compliance, contract design development, construction administration, maintenance, and reporting requirements. Section 1. Bioretention Unit Project A) CITY shall design, administer /construct and implement a project that improves the water filtration and carrying capacity of an existing roadside open channel next to Highway 101 near north of Corona Road overcrossing for a distance of 550 linear feet, approximately 25 -30' in width. The project shall be based on the conceptual proposal that was approved by the San Francisco RWQCB (Attachment 1). The Bioretention Unit shall provide stormwater treatment for a minimum of 7.19 acres of equivalent of highway impervious surface. B) The Bioretention Unit consists of the following elements: a. Retrofit of existing drainage system, which includes improvement of existing roadside open ditch and existing pipes b. Drainage structures to allow the inflow of stormwater into the Bioretention Unit and the outflow from the Bioretention Unit into CITY drainage system c. Construction of Bioretention Units with total minimum area of 30,000 SQFT of, which will include surface planting, tree, and shrub planting around the Bioretention Units d. Installation of access road to be used for maintenance of the Bioretention Unit e. Chain -link fence and gate for maintenance access Section 2. Environmental Compliance A) CITY will be the California Environmental Quality Act (CEQA) Lead Agency and CALTRANS will be the CEQA responsible agency for the Bioretention Unit project which will be located outside of CALTRANS right of way. CITY shall be responsible for the preparation of the environmental documentation to comply with CEQA. CALTRANS shall review, comment, and concur (if applicable) with the environmental document. B).CITY shall obtain all necessary permits, agreements, or approvals from the applicable regulatory agencies for implementation of the Bioretention Unit as described in Section 1 of this Exhibit. C) CITY shall not construct the Bioretention Unit within any jurisdictional waters or wetlands. 12 District Agreement No. 4 -2557 Section 3. Bioretention Unit Project Design Development A) CITY shall prepare the Plans, Specifications and Estimates (PS &E) in accordance with guidelines, design standards, and requirements approved by the CITY, for the installation of the Bioretention Unit as outlined in Section 1 above. The PS &E completion shall be within one year starting the effective date of this Agreement. B) A copy of the PS &E for the Bioretention Unit shall be submitted to CALTRANS for CALTRANS' review, comment, concurrence and /or approval at appropriate stages of development. C) Sizing calculations for the Bioretention Unit that demonstrate proper flow or volume (or combination of flow and volume) that demonstrates the off -site stormwater treatment system treats an equivalent of 7.19 acres of highway impervious surface shall be submitted to CALTRANS for CALTRANS' review, comment, approval and /or WRCB approval at appropriate stages of development. Section 4. Construction Administration A) CITY shall advertise, award, and administrate the construction contract for the Bioretention Unit project according to the PS &E. B) CITY shall notify CALTRANS in writing five (5) calendar days prior to the construction start date of the Bioretention Unit project. C) CITY shall notify CALTRANS in writing and obtain CALTRANS' approval prior to making any changes to the approved PS &E. D) CITY shall, within 180 calendar days following the contract completion and acceptance of the construction, furnish CALTRANS with a complete set of "As- Built" plans for the Bioretention Unit. The submittal must also include all CALTRANS requested contract records, including survey documents and Records of Surveys (to include monument perpetuation per the Land Surveyor Act, section 8771). CITY shall submit a complete set of acceptable full -sized reproducible "As- built" plans on a CD -ROM in MicroStation or AutoCAD format. Section 5. Maintenance and Reporting Requirements A) Following completion of the Bioretention Unit construction, the Bioretention Unit shall be incorporated into CITY's inventory of stormwater treatment facilities and shall be maintained by the CITY thereafter. B) CITY shall ensure the Bioretention Unit is properly maintained following Alameda County C.3 Stormwater Technical Guidance to enable their full pollutant removal functionality, including but not limited to, effective removal of trash, suspended solids and petroleum -based pollutants, for no less than 20 years. C) CITY shall submit written bank verification to CALTRANS that CITY has deposited $40,000.00 into an interest bearing account for the maintenance of the Bioretention Unit installed within the CITY for a 20 year life of service. 13 District Agreement No. 4 -2557 D) CITY shall submit a report in electronic format detailing the installation of the Bioretention Unit within ten (10) days following completion of all construction work, including but not limited to the following information: 1. Date of construction completion 2. Total cost of the project 3. Name, address, and telephone number of the maintenance entity that will be maintaining the Bioretention Unit 4. Any changes that occurred during construction (if any) E). CITY shall submit an annual maintenance report in electronic format on the Bioretention Unit to CALTRANS by October 1St each year for twenty (20) years including, but not limited to the following information: 1. Date of maintenance 2. List of maintenance activities performed 3. General operation and condition of Bioretention Unit 4. Any recommendations based on the maintenance review It is acceptable for the CITY to provide an excerpt of their annual National Pollutant Discharge Elimination System (NPDES) report to the San Francisco Bay Regional Water Quality Control Board which also documents maintenance activities of water - treatment measures in the CITY system. The excerpt must address the items listed above in the annual maintenance reporting. 14 District Agreement No. 4 -2557 EXHIBIT B COST BREAKDOWN (AUGUST 17, 2015) City of Petaluma — Old Corona Road /Industrial Ave Storm Water Treatment 15 Item Unit Cost Cost Comments Design Consultant Design - Bio- Retention Unit $187,000 25% of construction cost Environmental Clearance Document $40,000 Subtotal Design $227,000 Construction Bio- Retention Unit near intersection of Old Corona Road and Industrial Ave. Pipe Installation, Drainage Structures, Bio - Retention Unit, Planting $745,000 Construction Contingencies 15% of construction costs $112,000 Subtotal Construction $857,000 Support Cost Project Administration $ 15,000 Design Support Cost $15,000 Construction Support Cost $40,000 Subtotal Support Cost $70,000 Maintenance Annual maintenance 20 years $225,000 Annual maintenance cost of $11,250/ unit Total $1,379,000 15 District Agreement No. 4 -2557 EXHIBIT C PROPOSED OFF -SITE STORMWATER TREATMENT LOCATION MAP 16