Inflow and Infiltration/ Sewer Overflow Reduction Program Part 3. November 10, 2011

Transcription

1 Inflow and Infiltration/ Sewer Overflow Reduction Program Part 3 November 10, 2011

2 Our Agenda for this Meeting Brief recap from Parts 1 and 2 Additional approaches to consider for I/I Reduction: PSL Inspection Program Summary and comparison of current and additional approaches to I/I Reduction Results from Limited Analysis to Identify Optimal Approach December 8 Board Meeting Questions/Discussion

3 Recap from Parts 1 and 2

4 Current I/I Reduction Programs from Part 1 Smoke Testing CCTV Inspection Sewer Main and Lower Lateral Rehabilitation Offer property owners opportunity to have upper laterals included in sewer rehabilitation projects at a lower cost but paid by the property owner. Realtor Disclosure Form: Buyers are advised to obtain a video inspection of the sewer lateral.

5 Additional Approaches to I/I Reduction from Part 2 Public Outreach and Education I/I Reduction incentives/disincentives to rate structure Include upper lateral in gravity sewer rehabilitation projects Public ownership of residential private sewer laterals

6 Additional Approach to Consider for Increased I/I Reduction

7 Additional Approach #5 Private Sewer Lateral Program Description: Reduce I/I from private sewer laterals (PSL) through a program of mandated periodic testing and required rehabilitation/replacement of PSLs that fail the test. Comments: Effectiveness at reducing I/I is dependent on program requirements (e.g. testing triggers and passing criteria). Initial effectiveness at reducing I/I in a given area is limited until all of the gravity sewer mains, manholes, lower laterals, and upper lateral subject to I/I in that area are rehabilitated or replaced. Potential for overlapping requirements with City/County Building Code Enforcement responsibilities.

8 Examples of Failed PSLs

9 Key Components of Any PSL Program Triggers What actions require a PSL to be tested? Standards What methods must be used to test the PSL? What criteria must be met for the PSL to pass the test? What are the actions and timeframes for the private property owner to bring their PSL into compliance with the standards? Verification Who verifies that the PSL passes or fail the test? Control Mechanism What mechanism is used to demonstrate that a private property owner has met the requirements? What Is the required frequency for re testing?

10 Key Components of Any PSL Program (cont d) Legal Authority What is the District s legal authority in the area? Require testing Enforce compliance Set and collect fees What authority is delegated to District staff? What provides due process for private property owners? Policies and Procedures What process will be followed? Who are the responsible individuals and what are their responsibilities? What are the standards?

11 Examples of Common Approaches Component Common Approaches Triggers Change of customer Standards Evidence of PSL problems observed during sewer main inspection History of PSL overflows to public right of way Property located in area with elevated I/I Property located upstream of capacity caused SSO Remodel above a threshold value Sale of property Acceptable test methods and passing criteria Air test: minimal loss of air pressure in 5 minutes CCTV inspection: no evidence of root intrusion, infiltration, or structural defects Water test: no detectable leakage in 5 minutes

12 Examples of Common Approaches (cont d) Component Common Approaches Standards Actions and timeframes for PSL failing the test (cont d) Private property owner must repair or rehabilitate the PSL at their sole expense and re test it within XX days of being notified of not passing the test Verification Test witnessed by District Staff Control Mechanism Test witness by District Contractor Test results or CCTV video reviewed by District Staff Test results or CCTV video reviewed by District Contractor Proof that PSL is in Compliance Certificate of Compliance District database

13 Examples of Common Approaches (cont d) Component Testing Frequency Legal Authority Policies and Procedures Common Approaches Repair: 7 15 years Rehabilitation/Replacement: years Ordinance Legal Authority to require testing and enforce compliance Staff authority Due Process Ability to collect fees Board adopts policies and procedures Staff provides policies and procedures to Board Staff prepares and maintains policies and procedures

14 Sample PSL Inspection Process

15 Assumptions Used to Estimate Staffing and Cost 9,200 PSLs 8,800 Residential 400 Commercial Annual number of inspections 500 per year Change of Customer 130 per year Remodel > $25, per year for Other triggers 80% of PSLs tested fail the test PSL testing and rehabilitation costs $4,000 each

16 Projected Staffing, Cost, and Cost Effectiveness Parameter Value Annual Number of Inspections 660 Estimate Time to Inspect all PSLs 20 years Estimated Annual District Cost $200,000 Estimated Staffing* 2 FTEs Estimate Annual Cost to Property Owners $2,800,000 Estimated Cost per GPD of I/I Eliminated** > $100,000 * Staffing expected to vary seasonally between 0.5 FTE and 3 FTEs if District witnesses each test. District staff review of CCTV inspection video would require 1 FTE. ** Cost effectiveness based on initial effectiveness of 25% I/I reduction. Effectiveness is anticipated to increase in areas where comprehensive rehabilitation has been achieved.

17 Comparison of Current and Additional Approaches to I/I Reduction

18 Comparison of Approaches to I/I Reduction Approach Estimated Total Annual Cost Estimated Total Cost per GPD I/I Eliminated CCTV Inspection Minimal Additional Cost Minimal Smoke Testing $60,000 $0.50 Sewer Main and Lower Lateral Rehabilitation Including Upper Laterals if Property Owners Opts In Sewer Main and Lower Lateral Rehabilitation $750,000 $7 $550,000 $8 Public Ownership of PSLs $4,100,000 $17 Public Outreach and Education $50,000 $19 Realtor Disclosure Form $200,000 $22 PSL Inspection Program $2,800,000 > $100,000 Add I/I Reduction Incentives to Rates Unknown Unknown

19 Total Cost vs. I/I Reduction Potential

20 Total Cost vs. I/I Reduction Potential

21 Total Cost vs. I/I Reduction Potential High Cost/Small Impact High Cost/Moderate Impact Low Cost/Small Impact Low Cost/Moderate Impact

22 Summary of Observations The current I/I reduction programs, at their current scale, are not capable of reducing I/I by more than 1 MGD over the next 8 years. The additional I/I reduction programs that have been identified are not capable of reducing I/I by more than an additional 1 MGD over the next 8 years. Reducing I/I by 12 MGD over the next 8 years would require increasing the gravity sewer rehabilitation program from 0.5 miles per year to 6 miles per year at a cost of approximately $50 million.

23 Preliminary Results from Limited Analysis to Identify Optimal Level of I/I Reduction

24 Assumed Future Scenario Renew Current NPDES Permit in 3 Years (2014) 2015 NPDES permit ( ) May require actions to eliminate blending Likely Approach to Eliminating Blending New Prohibition: Sewer system peak flow must not exceed secondary treatment capacity Compliance required by next permit renewal (2021) Compliance Actions Sewer System I/I Reduction TP Capacity Upgrade Combination of Actions Current level of I/I reduction Upgrade TP capacity

25 Assumed Future Scenario (cont d) Worst Case Eliminate blending by 2020 (8 years) Actions required Add sewer system storage and/or reduce I/I to reduce peak flow to 8 MGD Increase TP storage and treatment capacity 20 MGD Combination of actions Estimated Cost of these Actions Reduce peak flow to 8 MGD by eliminating 12 MGD of I/I $60 million Increase TP capacity by 12 MGD to 20 MGD $15 million

26 Outcome from Limited Analysis

27 Outcome from Limited Analysis Lowest Total Capital Cost at MGD

28 Summary of Results of Limited Analysis Current I/I reduction programs are appropriate in the near term but do not address the long term increase in I/I as the sewer system ages. Increasing the secondary treatment capacity through onsite storage and upgraded secondary treatment facilities has the lowest total capital cost. The optimum secondary treatment capacity needed to avoid blending would be MGD. If the treatment capacity cost estimate is 50% low, then the optimum treatment plant capacity would be MGD and some additional I/I reduction would be appropriate.

29 Other Possible Actions Consider flow monitoring over next 3 5 years to provide information regarding I/I at basin and sub basin levels. Provide cost saving targeting of rehabilitation projects so that District only fixes what actually needs fixing. Use information to construct hydraulic model to identify optimal size and configuration of storage facilities.

30 What s Next?

31 December 8 Board Meeting Discuss/clarify information from the first three presentations. Review and discuss the draft Decision Matrix regarding changes and/or additions to the I/I Reduction Programs. Provide direction to District Staff.

32 Any Remaining Questions?

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