WVSD SANITARY SEWER REHABILITATION PROGRAMWVSD SANITARY SEWER REHABILITATION PROGRAM

2006 Sewer Smart Summit2006 Sewer Smart Summit

Presented byPeter V. Sevcik, P.E.

West Valley Sanitation District

Campbell, California

West Valley Sanitation DistrictWest Valley Sanitation District Special District formed in 1948 to provide sewer Special District formed in 1948 to provide sewer service in western Santa Clara Valleyservice in western Santa Clara Valley 29 square mile service area with 120,700 29 square mile service area with 120,700 customers and 44,500 connectionscustomers and 44,500 connections District facilities include 426 miles of sewer District facilities include 426 miles of sewer mains and 250 miles of lateralsmains and 250 miles of laterals Average age of pipe in system estimated at Average age of pipe in system estimated at approximately 45 years, some as old as 90+ yearsapproximately 45 years, some as old as 90+ years Majority of pipe 6 inch diameter vitrified clayMajority of pipe 6 inch diameter vitrified clay

Condition AssessmentCondition Assessment 2000 Basin Rehabilitation Strategic Plan2000 Basin Rehabilitation Strategic Plan

–Prioritized the order in which areas were to be televised Prioritized the order in which areas were to be televised based on dry weather flow data and maintenance historybased on dry weather flow data and maintenance history

In-House CCTV Inspection Program In-House CCTV Inspection Program –District is in the process of televising entire systemDistrict is in the process of televising entire system–Identifying pipe that needs to be replaced or Identifying pipe that needs to be replaced or rehabilitatedrehabilitated–Annual goal to televise 200,000 feetAnnual goal to televise 200,000 feet–930,000 feet televised since 2001930,000 feet televised since 2001

Project PlanningProject Planning Review of CCTV Inspection Review of CCTV Inspection

–Engineer reviews digital CCTV data and videoEngineer reviews digital CCTV data and video–Group project areas by sub-basin and prioritize by Group project areas by sub-basin and prioritize by severity of defects identifiedseverity of defects identified–Approximately 12,000 to 15,000 feet per projectApproximately 12,000 to 15,000 feet per project

Plans and Specifications Plans and Specifications –In-house with consultant assistanceIn-house with consultant assistance

Geotechnical ReportGeotechnical Report–Determines whether trenchless methods possibleDetermines whether trenchless methods possible

Project PlanningProject Planning Opportunity to optimize system configurationOpportunity to optimize system configuration Annual capital expenditure of $2,500,000 for Annual capital expenditure of $2,500,000 for rehabilitation not including trunk sewersrehabilitation not including trunk sewers CIP funding built into rate structure CIP funding built into rate structure 103,000 feet rehabilitated to date at a cost of 103,000 feet rehabilitated to date at a cost of $11.3 million$11.3 million Starting in FY 06-07, annual capital expenditure Starting in FY 06-07, annual capital expenditure increasing to $4,000,000 per yearincreasing to $4,000,000 per year

Rehabilitation OptionsRehabilitation OptionsUtilized by WVSDUtilized by WVSD

Cured-In-Place Pipe (CIPP)Cured-In-Place Pipe (CIPP) Pipe BurstingPipe Bursting Pipe ReamingPipe Reaming Horizontal Directional Drilling (HDD)Horizontal Directional Drilling (HDD)

Cured-In-Place PipeCured-In-Place Pipe

Resin-saturated tube inserted into existing pipeResin-saturated tube inserted into existing pipe Tube is expanded and cured by steam or hot waterTube is expanded and cured by steam or hot water Final product is pipe within a pipeFinal product is pipe within a pipe Existing sewer laterals are reinstated internally Existing sewer laterals are reinstated internally with a remote controlled cutterwith a remote controlled cutter No excavation requiredNo excavation required No change in pipe capacityNo change in pipe capacity

Pipe BurstingPipe Bursting

Utilizes a heavy-duty winch to pull a cracking Utilizes a heavy-duty winch to pull a cracking head that breaks the existing pipe into pieceshead that breaks the existing pipe into pieces New pipe is simultaneously pulled into the newly New pipe is simultaneously pulled into the newly formed void formed void Allows use of larger diameter pipe Allows use of larger diameter pipe Excavation limited to entrance and exit pits as Excavation limited to entrance and exit pits as well as lateral connectionswell as lateral connections Can also be used to replace lower lateralCan also be used to replace lower lateral

Pipe ReamingPipe Reaming Utilizes a horizontal directional drilling machine Utilizes a horizontal directional drilling machine and modified cutter headand modified cutter head Grinds existing pipe into smaller pieces that are Grinds existing pipe into smaller pieces that are carried out with other excess materials by drilling carried out with other excess materials by drilling fluid to exit pit fluid to exit pit New pipe is simultaneously pulled into placeNew pipe is simultaneously pulled into place Allows use of significantly larger diameter pipe to Allows use of significantly larger diameter pipe to replace existing pipereplace existing pipe Excavation limited to entrance and exit pitsExcavation limited to entrance and exit pits

Horizontal Direction DrillingHorizontal Direction Drilling

Utilizes a horizontal directional drilling machine Utilizes a horizontal directional drilling machine to install a new pipe where no pipe currently existsto install a new pipe where no pipe currently exists Process starts with pilot hole drilled to desired Process starts with pilot hole drilled to desired gradegrade Hole is then enlarged by back reaming while new Hole is then enlarged by back reaming while new pipe is simultaneously pulled into placepipe is simultaneously pulled into place Not recommended for gravity sewers with a Not recommended for gravity sewers with a design slope of less than 1.5%design slope of less than 1.5%

Rehabilitation Benefits From Rehabilitation Benefits From Collection System ViewpointCollection System Viewpoint

Reduced potential for SSOsReduced potential for SSOs Reduced O&M costsReduced O&M costs Potential to increase capacityPotential to increase capacity Improved customer serviceImproved customer service Continued protection of water qualityContinued protection of water quality

Questions?Questions?

Peter V. Sevcik, P.E.Peter V. Sevcik, P.E.

West Valley Sanitation DistrictWest Valley Sanitation District

408-378-2407408-378-2407

psevcik@westvalleysan.orgpsevcik@westvalleysan.org