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Home My WebLink About11/17/2009, C3 - WASTEWATER COLLECTION SYSTEM FLOW MONITORING SERVICES - REQUEST FOR PROPOSALS council M�in�D.,. aagenba nepont " o CITY O F SAN LUIS O B I S P O FROM: Carrie Mattingly, Utilities Director Prepared By: Jennifer Metz, Utilities Project Manager Bud Nance, Wastewater Collection Supervisor SUBJECT: WASTEWATER COLLECTION SYSTEM FLOW MONITORING SERVICES—REQUEST FOR PROPOSALS RECOMMENDATION 1. Approve the request for proposals (RFP) for Wastewater Collection System Flow Monitoring Services and authorize its issuance, and; 2. Authorize the City Manager to award a two-year contract, if the selected proposal is within the approved budget of$150,000; $75,000 each fiscal year in 2009-11. DISCUSSION Background Inflow is water that enters the collection system at points of direct connection (non-soil) such as around manhole covers or through illegal connection of roof drains, downspouts, or landscape drains. Inflow is usually induced by a rain event. Infiltration is water that flows through the ground into the collection system usually through cracks in public sewer mains and/or private sewer laterals. Cracks in sewer pipes may be caused by age-related deterioration, loose joints, poor design, installation or maintenance errors, damage, or root infiltration. Water can enter these cracks wherever sewer lines lie beneath ground water tables or the soil above the sewer system becomes saturated. The City's wastewater collection system and the Water Reclamation Facility (WRF) have long experienced problems associated with excessive wet weather infiltration and inflow (I & I). I & I overloads the collection system during heavy rains and can result in sewage spills. In the past, the City minimized spills by installing relief sewers. However, relief sewers only serve to convey the problem to the WRF. During periods of significant rain events, the WRF can become hydraulically overwhelmed, increasing the chance of effluent violations and the release of partially treated wastewater to San Luis Obispo Creek. Because all water entering the WRF must be treated as wastewater, I & I has a significant impact on operating expenses and drives the need for capital expenditures. Actions Taken With Council's support over the past 20 years, the City has made significant progress in reducing sanitary. sewer overflows and service interruptions. Ongoing comprehensive maintenance activities and capital improvement projects continue to improve the function of the wastewater C3 - I Council Agenda Report-RFP for Flow Monitoring Services Page 2 collection system. While the public sewer mains are routinely maintained, private sewer laterals that serve residences and businesses usually go much longer without inspection or repair. In 1989, Council directed staff to work toward elimination of I & I rather than designing and constructing additional relief sewers. In 1994, City staff completed a comprehensive investigation on a portion of the collection system in the northwest part of the City. This investigation showed that private sewer laterals were the most significant source of I & I. There are 138 miles of public sewer mains and an estimated 100 miles of private sewer laterals in the City. Many of these laterals are over 50 years old (50 years is an engineering standard for the useful life of a typical sewer pipe). In 1996, Council approved the Voluntary Service Lateral Investigation and Rehabilitation Program. To date, the program has dispensed around 1,000 reimbursements for lateral repair or replacement due to troublesome "orangeburg" pipe, structural deficiencies, and root intrusion. The homeowner benefits by receiving from the city free of charge: free construction permits, free technical advice and a rebate of one-half the cost of replacement or repair up to a maximum of $1,000 per property. This action benefits the City by reducing I & I from those laterals. Continued evidence of significant I & I indicates that this work alone has not been effective. Detailed studies to identify sources of I & I within the aging infrastructure have not been conducted since 1994. The proposed flow monitoring is an important next step in the long-term resolution of the I & I issue. Current Study The City is seeking proposals from firms to conduct wastewater collection system flow monitoring to quantify and analyze wastewater flows in the City's 18 flow basins. See Attachment 1 for a map of existing flow basins and potential monitoring locations. The proposed analysis will determine the areas in the City experiencing the highest levels of inflow and infiltration and will assist the City in focusing its resources. The approved budget for the two-year study is $150,000; $75,000 each fiscal year in 2009-11. The RFP for professional services includes both dry- and wet-weather flow monitoring of each of the City's flow basins in order to differentiate flows during a rain event from normal dry season flows. The study will also quantify whether excess flows are inflow, instantaneous flow peaking usually associated with direct connections to the collection system, or infiltration, a prolonged elevation of flows related to high groundwater levels leaking into the collection system. The City is seeking comprehensive flow monitoring services (installation, testing, calibrating, monitoring, downloading data, and data analysis). Based on the findings of the analysis, the consultant will quantify the excess I & I entering each of the flow basins, rank basins by the severity of I & I entering each basin, and break them into sub-basins. Similar data analysis will follow sub=basin flow monitoring where the consultant will quantify the excess I & I entering each of sub-basin and rank sub-basins by the severity of I & I. 0 3 -a f; Council Agenda Report- RFP for Flow Monitoring Services Page 3 The consultant will prepare a report summarizing the flow monitoring effort and the data collected. The report will also include the consultant's recommendations for future programs to reduce I & I citywide or specific programs to address a more localized I & I problem. After completion, staff will return to Council with the findings of the study and recommendations for future programs to reduce I& I. Evaluation and Selection Process Proposals are due no later than December 10, 2009. Based on the evaluation criteria set forth in the RFP, proposals will be reviewed and, if necessary, finalists will be invited for a follow-up presentation/interview before a review committee. The review committee will be composed of staff from the City's Utilities department. Reference checks will be conducted. Based on the results of the selection process, a recommendation will be made to the City Manager to award the contract. It is anticipated contract award will be made during January 2010. Prospective Proposers In addition to publishing a formal notice requesting proposals, the RFP will be mailed to firms specializing in these services. A list of prospective firms is part of the RFP. FISCAL IMPACT This project is estimated to cost $150,000 over a two year period. An Infiltration/Inflow Reduction Study, including flow monitoring and development of measurable projects to reduce infiltration and inflow, was approved as part of the 2009-2011 Financial Plan, Significant Operating program Changes, Appendix A, pages 51-53. A total of $150,000 is budgeted; $75,000 in each fiscal year. ALTERNATIVES 1. Provide direction to staff to amend the RFP for Wastewater Collection System Flow Monitoring Services and approve the RFP based on those changes. Staff has identified a scope of work focused on gathering data to address the inflow and infiltration issue. This alternative is not recommended. 2. Deny the issuance of the RFP for Wastewater Collection System Flow Monitoring Services. This alternative is certainly feasible, although this study is an important next step in the reduction of inflow and infiltration. This alternative is not recommended. ATTACHMENT Wastewater Collection System Flow Basins & Monitoring Locations ON FILE IN THE COUNCIL OFFICE Request for Proposals for Flow Monitoring Services . 013 -3 Attachment E F G H 3 K L M N 0 P 3 � I CILy o � san 6s onispo 5 Y I � s I 6 � a 9 � 9 is � 10 '- \ ti4_ 1 u1 Ai v' r L' _r ~ / 13 L'r 3 g 14 'C \ �•jJ 14 15 I is 3 -_--- -- ----_—_ --_�- —_ _- - 16 16 11r 1 d n n \H ^ 8 is I e i I Y'�T b � -X I j YOCNtBNtY t10LO J ® � I Coulif utaeOtf i9 `�" b n • 19 arvuwm I i I 20 SLOG S -- - - — ---- - - - --- — E F G H 1 1 K L M N O IP Wastewater Collection System Flow Basins & Monitoring Locations 18 Flow Basins (Differentiated by color) O Potential Flow Monitoring Locations (with Manhole ID) Source:City of San Luis Obispo Utilities Department.,Wastewater Collections,2009. C3-q