Infiltration and Inflow Study Scope of Work

Transcription

1 Prject Descriptin Infiltratin and Inflw Study Scpe f Wrk The City f San Mate (City) is currently under a Reginal Water Quality Cntrl Bard (RWQCB) Cease and Desist Order (CDO) requiring imprvements t its cllectin system t eliminate sanitary sewer verflws. The City sewer system and wastewater treatment plant have experienced high flws due t infiltratin and inflw (I/I) during peak strm events. As part f the City s Clean Water Prgram, an I/I reductin prgram is planned, where the gal is t identify and eliminate the I/I surces in rder t help achieve certificatin in accrdance with the CDO. The scpe f wrk fr this prject includes the fllwing: Prject management Cmpiling and analyzing existing data (e.g., flw mnitring, CCTV) t identify areas f relatively high cntributins f I/I. Perfrming field wrk including flw mnitring and surce detectin activities (e.g. smke testing) t evaluate the I/I reductin ptential f fcused rehabilitatin. Investigating the salinity issues experienced in the Basin C. Investigating ptential effectiveness f replacing sewer laterals system-wide. Prviding results t the City that are cmpatible with the City s current methds, frmats r sftware. Prviding necessary data t the City fr recalibratin f the cllectin system hydraulic mdel Task 1 Prject Management In additin t the services described in this scpe f wrk, the Cnsultant will als be respnsible fr general prject management services t be perfrmed thrughut the prject. These services include the fllwing: Prject crdinatin with City and Clean Water Prgram staff. Submissin f a wrk breakdwn structure (WBS), which includes a matrix indicating the budget amunts and man-hurs fr each task. The apprved WBS shall frm the basis fr reprting the status f each task in the mnthly prgress reprt and the prject invices. Submissin f mnthly prgress reprts that shall include wrk cmpleted, upcming wrk, prject issues, budget, and schedule status, ptential changes, and ther imprtant prject infrmatin. Submissin f mnthly invices that dcument the man-hurs and billing rates fr staff fr each task in the WBS, as well as verhead, prfit, and any direct csts. A summary with budget spent and remaining as well as current and previus billing perid invicing shuld als be included. Prject schedule updates with a detailed prject cst and resurce-laded schedule capable f calculating earned value that indicates prject start and finish dates, and WBS tasks. Quality cntrl. The Cnsultant will be required t develp a prject-specific Quality Management Plan (QMP) that will address the prcesses, prcedures, and persnnel engaged in quality cntrl. The Cnsultant shall establish and mnitr effective implementatin f the quality requirements fr the prject and be respnsible fr submitting adjudicated QC review frms t the City. Preparatin f a health and safety plan fr Cnsultant staff wrking n the prject. The safety plan shall address Cnsultant, City, and Cnsultant subcntractr field activities. Attendance at regularly scheduled meetings. Facilitatin f a kickff meeting t discuss wrk t be accmplished under this study, t review existing City infrmatin (knwn I/I prblem areas, high pririty areas, flw mnitring histry, CCTV recrds,

2 PAGE 2 prject files, recrd drawings, maintenance recrds, etc.), begin develpment f the plan frward, and develp prtcls and expectatins. Preparatin f a wrk plan with milestnes, meetings, submittals, and site visit dates addressing prject rganizatin and management, technical apprach, data cllectin plan, ntificatin prcedures and activity schedule. Preparatin f a risk register that cmpiles ptential risks n the prject and their likelihd and impact. Task 2 Inflw/Infiltratin Data Review In 2013, V&A perfrmed flw mnitring fr the City f San Mate and summarized the results in the Sanitary Sewer Flw Mnitring and Inflw/Infiltratin Study. V&A mnitred flw and rainfall ver a perid f apprximately tw mnths using 30 flw mnitrs and six rain gauges spaced thrughut the city, determining dry and wet weather flws, peaking factrs and ther data at each lcatin. Under this Task, the Cnsultant shall cmpile and analyze histric flw mnitring and rainfall data (including the V&A study) t quantify the fllwing fr each flw mnitring basin and fr significant rain events: Peak flwrates Peaking factrs Rainfall return ratis (%r) Ttal (mnitr) and net (basin) rainfall dependent inflw and infiltratin (RDII) vlumes Nrmalized RDII t length f pipe Nrmalized RDII t length f pipe per inch f rain Ttal and net grundwater infiltratin (independent f rain events). Based n this analysis and the review f the City s CCTV data, the Cnsultant shall rank each f the flw mnitring basins fr verall I/I severity and prvide a recmmendatin fr which City sewer basins and subbasins (as data allws) shuld be designated fr additinal effrts in identifying and crrecting I/I. Task 3 Flw Mnitring, Detectin Activities, and Rehabilitatin Based n data frm previus flw mnitring, there are indicatins that Basin C (brdered by Highway 101, 3 rd Avenue and the Marina Lagn) experiences the mst I/I in the city. In additin, the basin has experienced salinity prblems as well. Therefre, the City wuld prefer that this basin be included as ne f the areas in mving frward with further studies, and if needed, rehabilitatin. The Cnsultant shall identify sub-basins r areas within Basin C, and ther recmmended flw basins r areas that warrant an extensive rehabilitatin effrt. The wrk in these areas will cnstitute a pilt test. The Cnsultant shuld first determine if additinal flw mnitring is required in relatin t the areas f anticipated wrk. In additin, the Cnsultant shall develp prgram bjectives, an implementatin plan and a schedule fr the pilt wrk generally cnsisting f the fllwing: Pre-rehabilitatin flw mnitring Perfrmance f necessary surce detectin activities (e.g. smke testing, dye water studies, additinal CCTV). Rehabilitatin

3 PAGE 3 Cmmunicatins with City staff will be essential prir t implementatin f the pilt test plan as the wrk may be perfrmed n laterals in additin t mains and may require access t private prperty t dcument findings (e.g. smke frm smke test leaking frm private sewer lateral). Public ntificatins will be a significant prtin f the wrk. In additin, several crdinatin meetings with City staff and public utreach meetings will be required. The fllwing tasks are dependent n what is determined by the Cnsultant as the necessary curse f actin. At cmpletin f Task 3, the Cnsultant shall prvide the City with all investigative data btained during this prject. This infrmatin will be used t update the City s GIS and supprt maintenance f the City s InfWrks hydraulic mdel. Task 3.1 Pre-rehabilitatin Flw Mnitring and Data Analysis Shuld the cnclusins frm Task 2 indicate that additinal flw mnitring is needed within the areas recmmended fr the pilt test (t include Basin C), the Cnsultant shall prepare a flw mnitring plan. Task Pre-rehabilitatin Flw Mnitring The purpse f this task is t establish a baseline frm flw mnitring prir t substantive rehabilitatin wrk being perfrmed. The pilt area shuld be islated s that the relative amunt f I/I and grundwater can be determined. It shuld be assumed that 60 days f flw mnitring will be required t adequately capture the rain impact. Ttal disslved slids r electrical cnductivity shuld als be mnitred in select lcatins, especially in lcatins clser t the Bay prne t seawater intrusin, like Basin C. It shuld be assumed that up t three (3) field prbes with data lgging capabilities will be used. Data cllectin will ccur ver the same perid as the flw mnitring, but if the mnitring needs t cntinue beynd the flw mnitring perid t capture unique flw characteristics, this shuld be accmmdated. In additin, the Cnsultant shall btain current grundwater data in the cllectin system at available grundwater mnitring wells fr relating gauged flw rates and infiltratin t grundwater levels during the prerehabilitatin flw mnitring perid. The Cnsultant shall btain rainfall mnitring data t cmpare variatins in gauged flw rates t rainfall intensity, ttal vlume and rate per event. Rainfall data shuld be cllected specific t the study area and will likely require a minimum f tw (2) gauges. Task Flw Data Analysis Fr any additinal flw mnitring btained, the data will be used t characterize I/I (critical t the identificatin and priritizatin f necessary surce detectin activities) and supprt future mdel calibratin effrts. Therefre, the cntinuus flw mnitring data shall be analyzed by the Cnsultant t identify and reprt the fllwing: Dry-weather Diurnal curves (hurly mnitr averages) Net (basin) and ttal (mnitr) average daily flws Inflw/infiltratin fr each strm event Grundwater infiltratin flw Peaking factrs rainfall return (%r)

4 PAGE 4 Vlume: ttal and nrmalized (e.g., t length f upstream pipe) The Cnsultant shall summarize the findings and recmmendatins f the flw mnitring. The fllwing infrmatin shuld be included: Summary tables and estimates f quantities f extraneus flws and gauging results Descriptin f prblems (verflws, bypasses, surcharging, etc.) within the system, nting any past studies and rehabilitatin wrk. GIS data delineating flw mnitring basins, gauging lcatins, etc. Installatin lgs fr all flw mnitrs Summary f data prcessing methds and where emplyed Electrnic submittal f final prcessed data t the City At the cnclusin f this wrk, the Cnsultant shall recmmend surce detectin activities in the target areas. Task 3.2 Detectin Activities, Inspectin and Rehabilitatin Based n the findings f previus tasks, this task invlves the implementatin f the I/I rehabilitatin f the pilt test area. Task Detectin Activities and Inspectin The Cnsultant shall implement, r manage subcntractrs, t perfrm the recmmended activities t detect ptential I/I surces and determine effective remval alternatives: Surce detectin activities (e.g., smke testing, dye water, CCTV) in mains and laterals generally perfrmed during perids f lw grundwater (dry seasn) System inspectins (e.g. manhles, pipeline acustic sunding) The Cnsultant shall submit a field reprt based n the activities and inspectins perfrmed in this task. Prir t implementatin, the Cnsultant shall crdinate with the City t identify the acceptable data frmat and deliverables. The items in the reprt culd include, but is nt limited t, the fllwing: Smke testing methds, results, and inspectin frms (including phtgraphs, maps, and databases) Acustic sunding methds, results, and databases Public relatins prgram dcumentatin and implementatin Manhle inspectin methds, results, and inspectin frms (including phtgraphs, maps, and databases) Dye testing methds, results, and field frms (including phtgraphs, maps, and databases) CCTV methds, results, and inspectin frms (including phtgraphs, vides, maps, and databases) Dcumentatin f field inspectin prgress tracking Dcumentatin f sewer cleaning effrts, including methds, results, activity lgs and apprpriate cpies f trip tickets Database f defects identified with (at a minimum) lcatin, type, and severity Field data analysis reprt Task Rehabilitatin Pilt Prject Based n the analysis f the field data cllected, the Cnsultant shall identify specific assets fr repair r replacement t help alleviate I/I in the pilt area. The recmmended prjects may include public right-f-way

5 PAGE 5 repair r rehabilitatin (e.g. replacement, cured in place pipe, pipe bursting) as well as main and lateral repair r replacement n private prperty (e.g. rehabilitatin f mains in easements, rf r drain discnnects). Apprpriate trenchless technlgies shall be cnsidered fr the recmmended rehabilitatin prjects. The Cnsultant shall perfrm a cst-benefit analysis fr different I/I remval alternatives t cmpare I/I remved versus renewal cst. The Cnsultant shall prvide the City the fllwing: Maps f recmmended renewal lcatins Defect reprts fr each defect recmmended fr repair Summary f recmmended actin fr each defect Cst estimates f wrk required t repair defect Amunt f I/I remved fr each defect The Cnsultant will als be available t discuss and crdinate these results with the City s cllectin system facility planners. Task Pst-rehabilitatin Flw Mnitring The purpse f this task is t establish the effectiveness f the wrk perfrmed during the pilt test. This will likely nt ccur until a year and a half t tw years after the initial flw mnitring due t the time it wuld take t implement the rehabilitatin prjects. It will be accmplished by perfrming system mnitring f flw and rain. It is assumed that 60 days f flw mnitring will again be required t adequately capture the rain impact and assess the impact in the system due t the rehabilitatin wrk. Similar t the pre-rehabilitatin mnitring, the flw mnitring shuld be cnducted during the wet seasn maximizing the ccurrences f significant rain events. The same mnitring lcatins used in the pre-rehabilitatin mnitring will likely be used again augmented with additinal mnitrs as needed. The equivalent data analysis identified in Task Flw Data Analysis abve shall be perfrmed again by the Cnsultant. Task 4 Citywide I/I Rehabilitatin Cst-Benefit Analysis Based n the findings f the wrk described abve, the Cnsultant shall prvide the City with a recmmended cmprehensive and system-wide I/I Remval Plan that will include aspects f the fllwing: System perfrmance prir t rehabilitatin System perfrmance after rehabilitatin Analysis f the rain strms mnitred (i.e., cmparisn t intensity duratin plts fr San Mate) Cst benefit analysis f the wrk perfrmed during pilt study Recmmendatins t carry the I/I Remval prgram frward expanding the wrk t ther City basins including: Extraplatin f I/I results t ther basins in the City Resurce requirements (e.g. City staff, equipment, sftware) Cst estimates t expand the prgram Schedule and sequencing Cnstraints The recmmendatins will be cupled clsely with ther prgram dcuments t supprt a cmprehensive system management plan. In additin, the Cnsultant shall evaluate the ptential effectiveness f lateral replacement thrughut the City.

6 PAGE 6 The evaluatin shall include develpment f a private sectr I/I remval strategy that addresses, at a minimum, the fllwing: Public utreach Legal and plicy cnsideratins Resurces Inspectin and remval methds Funding Data acquired n laterals in the pilt study As part f the strategy, the Cnsultant shall develp cnceptual pre- and pst-rehabilitatin flw mnitring plans, allwing fr the cmparisn between pre-rehabilitatin and pst-rehabilitatin f private laterals.