Transcript WILDCAT CREEK TRUNK SEWER RELOCATION PROJECT

2006 Sewer Smart Summit
WVSD SANITARY SEWER REHABILITATION PROGRAM
Presented by
Peter V. Sevcik, P.E.
West Valley Sanitation District
Campbell, California
West Valley Sanitation District
Special District formed in 1948 to provide sewer
service in western Santa Clara Valley
 29 square mile service area with 120,700
customers and 44,500 connections
 District facilities include 426 miles of sewer
mains and 250 miles of laterals
 Average age of pipe in system estimated at
approximately 45 years, some as old as 90+ years
 Majority of pipe 6 inch diameter vitrified clay
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Condition Assessment
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2000 Basin Rehabilitation Strategic Plan
–Prioritized the order in which areas were to be televised
based on dry weather flow data and maintenance history
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In-House CCTV Inspection Program
–District is in the process of televising entire system
–Identifying pipe that needs to be replaced or
rehabilitated
–Annual goal to televise 200,000 feet
–930,000 feet televised since 2001
Project Planning
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Review of CCTV Inspection
–Engineer reviews digital CCTV data and video
–Group project areas by sub-basin and prioritize by
severity of defects identified
–Approximately 12,000 to 15,000 feet per project
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Plans and Specifications
–In-house with consultant assistance
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Geotechnical Report
–Determines whether trenchless methods possible
Project Planning
Opportunity to optimize system configuration
 Annual capital expenditure of $2,500,000 for
rehabilitation not including trunk sewers
 CIP funding built into rate structure
 103,000 feet rehabilitated to date at a cost of
$11.3 million
 Starting in FY 06-07, annual capital expenditure
increasing to $4,000,000 per year

Rehabilitation Options
Utilized by WVSD
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Cured-In-Place Pipe (CIPP)
Pipe Bursting
Pipe Reaming
Horizontal Directional Drilling (HDD)
Cured-In-Place Pipe
Resin-saturated tube inserted into existing pipe
 Tube is expanded and cured by steam or hot water
 Final product is pipe within a pipe
 Existing sewer laterals are reinstated internally
with a remote controlled cutter
 No excavation required
 No change in pipe capacity

Pipe Bursting
Utilizes a heavy-duty winch to pull a cracking
head that breaks the existing pipe into pieces
 New pipe is simultaneously pulled into the newly
formed void
 Allows use of larger diameter pipe
 Excavation limited to entrance and exit pits as
well as lateral connections
 Can also be used to replace lower lateral

Pipe Reaming
Utilizes a horizontal directional drilling machine
and modified cutter head
 Grinds existing pipe into smaller pieces that are
carried out with other excess materials by drilling
fluid to exit pit
 New pipe is simultaneously pulled into place
 Allows use of significantly larger diameter pipe to
replace existing pipe
 Excavation limited to entrance and exit pits

Horizontal Direction Drilling
Utilizes a horizontal directional drilling machine
to install a new pipe where no pipe currently exists
 Process starts with pilot hole drilled to desired
grade
 Hole is then enlarged by back reaming while new
pipe is simultaneously pulled into place
 Not recommended for gravity sewers with a
design slope of less than 1.5%
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Rehabilitation Benefits From
Collection System Viewpoint
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Reduced potential for SSOs
Reduced O&M costs
Potential to increase capacity
Improved customer service
Continued protection of water quality
Questions?
Peter V. Sevcik, P.E.
West Valley Sanitation District
408-378-2407
[email protected]