1. - SEWER REHABILITATION - A TEN-STEP STRATEGIC PLAN GEORGE KURZ, P.E., DEE 615-252-4441 GEKurz@bwsc.net * A significant portion of this work was conducted with CTE-AECOM as part of the Nashville Overflow Abatement Program 1991-2005

2. SEMINAR OBJECTIVE Teach a proven, successful strategy.

3. SUCCESSFUL REHAB FACTORS DEFINE GOALS EXTENSIVE FLOW MONITORING & STANDARD PROCEDURES LATERAL REHABILITATION “TARGETING” – STOP WATER MIGRATION ACCOUNTABILITY – VERIFY DESIRED RESULTS

4. TOTAL SYSTEM APPROACH - Nashville Policy -  GOAL: “CONTAINMENT” FOR FLOWS FROM 5- YEAR, 24-HOUR RAINFALL  POLICY: ALL SERVICE LATERALS CONNECTED TO THE REHABILITATED PIPES WILL BE RENEWED TO THE EASEMENT LINE OR THE PROPERTY LINE ALL MANHOLES CONNECTED TO REHABILITATED PIPES WILL BE RENEWED

5. Ten steps 1. Identify Goals 2.Select Target Area 3.Quantify Problem 4.Locate Defects 5.Select Pipe Segments 6.Estimate Cost-Benefit 7.Design & Install 8.Verify Performance 9.Follow-up Flow Monitoring 10. Calculate O & M Savings

6. 1 - IDENTIFY COMMUNITY GOALS PERIOD OF TIME: 2 YEARS ?, 5 YEARS ? RELATE TIME TO RAINFALL EVENT RETURN INTERVAL NO OVERFLOWS LEGALLY SANCTIONED “ELIMINATE OVERFLOWS AND BASEMENT BACKUPS”

7. 2 - SELECT TARGET AREA FLOW MONITORING NETWORK (~100,000 L.F.) CALCULATE OBSERVED & POTENTIAL I/I HYDRAULIC MODEL IDENTIFY CAPACITY PROBLEMS PRIORITIZE TRIBUTARY AREAS

8. CAPACITY LOST TO HINDERED FLOW

9. 3 - QUANTIFY PROBLEM CONDITIONS INTENSIVE MONITORING IN TOP PRIORITY TRIBUTARY AREAS (8,000 - 15,000 L.F.) OBSERVED AND POTENTIAL I/I ADDITIONAL CAPACITY PROBLEMS

10. WEST PARK PUMPING STATION - 32 mgd 1.6mgd Clifton 1 2.0 mgd Clifton 3 11 mgd West End 2.1 mgd White Br 1.5 mgd Sugartree 1 15.3 mgd Brentwood Sugartree 2 - 12.9mgd Murphy Rd.- 4.2mgd Clifton 4 - 1.3mgd Clifton 2 - 1.6mgd SUM OF TRIBUTARIES =53.5 mgd WEST PARK METER =32 mgd POTENTIAL I/I = 21.5mgd

11. I/I AFTER REHAB PIPE CAPACITY PROJECTED METER READING POTENTIAL I/I RESTRICTED FLOW Example: 52% I/I REMOVAL

12. “POTENTIAL” I/I I/I Which Cannot Enter the Sewer Because the Pipe is Already Overloaded! Overall I/I Removal Goals Monitor Depth & Velocity Extrapolated

13. DATA INTERPRETATION 24-hour rainfall more reliable than peak hour rain for predicting peak design I/I AMC – Antecedent Moisture Condition is critical for selecting valid rainfall events HINDERED FLOW - POTENTIAL I/I There are ways to correct for this, however the analyst must be aware of this condition Underestimating the peak flow can result in the inadequate design of new facilities Need to standardize criteria

14. COMPARISON OF RESULTS Peak-hour flow (24-hr rain vs. Peak-hr rain)

15. Which type rainfall pattern puts the most stress on the system – for a standard return interval, design storm? Summer ? Or Winter ?

16. Type II Rainfall* – Characterized by short-term, high intensity thunderstorms and also by long-duration frontal storms. * USDA-SCS 1986 TYPICAL RAINFALL

18. Design Storm Peak: 2-Yr, 24-Hr vs. 3-Hr Peak hour I/I from 2-Yr, 24-Hr Storm is 3.89 mgd with good level of confidence Peak hour I/I from 2-Yr, 3-Hr Storm is 2.35 mgd with poor level of confidence

19. 4 - LOCATE & IDENTIFY DEFECTS TELEVISE TARGET AREA SYSTEM (MAY BE CONCURRENT WITH MONITORING) CATEGORIZE DEFECTS WITH RESPECT TO I/I POTENTIAL

20. 4 - LOCATE & IDENTIFY DEFECTS (CONT.) “INVISIBLE” DEFECTS - ELECTRIC FIELD LEAK DETECTION, SEGMENTAL ISOLATION GROSS INFLOW (ROOF DRAINS, ETC.)

21. 5 - SELECT SEGMENTS FOR REHABILITATION CATEGORIZE & COLOR CODE LINES –3 OR MORE MAJOR DEFECTS –1-2 MAJOR DEFECTS –NO MAJOR DEFECTS “3 OR MORE” - RENEW ! CHECK ADJACENT SEGMENTS RENEWAL “INTENSITY” - RANGE OF 15- 20% FIRST ROUND

22. CONNECT THE DOTS > 3 DEFECTS < 3 DEFECTS 0 DEFECTS REHABILITATE ? ? ? ? 25 % intensity METER

23. HALT MIGRATION ! INVISIBLE DEFECT "DRY" DEFECT POTENTIAL LEAK LEAK LINING OR REPAIR "NEW" LEAKS REVEALED FOLLOWING TRADITIONAL REPAIRS SEWER REHAB STRATEGY:

24. 6 - ESTIMATE COST-BENEFIT COMPARE RENEWAL COSTS TO: O&M COSTS ($1.73 - $1.87/ 1,000 GAL) AT LEAST 50% I/I REMOVAL COSTS: –LINING (8-10” CIPP) ~ $43 / LF –LATERALS ~ $2,250 ea. (1/ 200 LF) –MANHOLES ~ $1,000 -1,300 ea. (1/200 LF) –ENGINEERING ~ 12% - 15% OF TOTAL (GROSS= ~ $132/ft rehab)

25. 7 - DESIGN & INSTALL REHAB HALT MIGRATION FROM OUTSIDE PIPE HALT MIGRATION (“TRACKING”) INSIDE PIPE PROVIDE SEAL AT MANHOLE JUNCTION RENEW SERVICE LATERALS (over 10,000 rehabilitated in Nashville)

26. LATERAL REHABILITATION EFFECTIVENESS DOWNINGTON, PA -area 5 38 laterals in 1,513’ CIP - 100% treated 97% reduction - 22 mg annually STEGE SAN. DIST, CA - subarea N 111 laterals in 13,400’ Slip-PE & MH - 100% 86% reduction NASHVILLE, TN - Oak Valley 63 laterals in 4,400’ CIP - 41% treated 77% reduction (20%-laterals) - 67 mg annually

27. 8 - PERFORMANCE TESTING AIR-TEST SEWER SERVICE CONNECTION ! –MOST VULNERABLE PART –NOT ACCEPTED UNTIL PERFORMANCE VERIFIED

30. 9 - FOLLOW-UP FLOW MONITORING QUANTIFY I/I REDUCTION STANDARDIZED I/I ANALYSIS TV DURING WET WEATHER RERUN HYDRAULIC MODEL DETERMINE IF DESIGN GOALS MET !

32. STANDARDIZED I/I ANALYSIS DEFINES LEVEL OF CONFIDENCE FOR PROJECTED I/I USES QA/QC CONTROLS THAT ARE SIMILAR TO “STANDARD METHODS” (nationally recognized)

33. Example: Typical Nashville Rainfall Event Analysis 7 day dry flow ADF= 0.3 mg 24-hr I/I =0.37 mg Peak-hr I/I =0.738 mgd 2.11” Rainfall (adjusted to match beginning of storm flow @ 0.99 mg) DRY WEATHER ADF WET WEATHER HYDROGRAPH

34. NASHVILLE REHABILITATION EFFECTIVENESS

35. EFFECTIVENESS (a “rule of thumb”) 15-20% REHABILITATION INTENSITY (including MH & laterals, & in deteriorated areas) ~ 8-10 MILLION GALLONS ANNUALLY per 1,000 ft. LINING or REPLACEMENT

36. 10 - CALCULATE O&M SAVINGS POSSIBLE 7-11 YEAR PAYBACK (construction) PROVIDES DATA FOR FUTURE PROGRAM PLANNING ACCOUNTABILITY TO COMMUNITY

38. SUCCESSFUL REHAB FACTORS EXTENSIVE FLOW MONITORING LATERAL RENEWAL TO EASEMENT “TARGETING” - LINING SELECTED BY OBSERVED DEFECTS, AGE, PROXIMITY, MIGRATION POTENTIAL, SURFACE WATER PERFORMANCE (AIR) TEST LINE & LATERAL

39. STRATEGIC GOALS MET I/I REDUCTION SSO REDUCTION STREAM IMPROVEMENT

40. NASHVILLE MEASURED RESULTS 3.6 billion gallons I/I eliminated annually 49.6% Annual I/I eliminated 53% 24-hour, 5-year I/I reduction 52.2% Peak-hour, 5-year I/I reduction For the 27 areas (94 miles) analyzed so far: