WVSD SANITARY SEWER REHABILITATION PROGRAM

1. WVSD SANITARY SEWER REHABILITATION PROGRAM 2006 Sewer Smart Summit Presented by Peter V. Sevcik, P.E. West Valley Sanitation District Campbell, California

2. 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

3. Condition Assessment 2000 Basin Rehabilitation Strategic Plan Prioritized the order in which areas were to be televised based on dry weather flow data and maintenance history 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

4. Project Planning 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 Plans and Specifications In-house with consultant assistance Geotechnical Report Determines whether trenchless methods possible

5. 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

6. Rehabilitation OptionsUtilized by WVSD Cured-In-Place Pipe (CIPP) Pipe Bursting Pipe Reaming Horizontal Directional Drilling (HDD)

7. 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

8. 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

9. 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

10. 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%

11. Rehabilitation Benefits From Collection System Viewpoint Reduced potential for SSOs Reduced O&M costs Potential to increase capacity Improved customer service Continued protection of water quality

12. Questions? Peter V. Sevcik, P.E. West Valley Sanitation District 408-378-2407 psevcik@westvalleysan.org