Agenda. Streamlining I/I Repairs in Berlin Charter Township.. Innovative Techniques

Transcription

1 Streamlining I/I Repairs in Berlin Charter Township.. Innovative Techniques MWEA Collections System Seminar September 2012 Presented by: Elaine Venema, PE Rich Grant, PE Agenda Discussion of the problems I/I Evaluation & SSES Ground-truthing of Results Overall Result - $$ Savings for the Twp Lessons Learned / Key Recommendations Questions 1

2 The Problems At a Glance New permit limits - December 2007 Prior to Dec. 2007, ammonia was report only New limits were hard to consistently achieve May-Sept 1.4 mg/l Oct-Nov 5.1 mg/l Plant wasn t originally designed to nitrify Operations staff worked hard to achieve compliance mostly successful for ammonia The Problems At a Glance High flows received at the WWTF Every spring, lasting for several weeks During heavy rain events Both infiltration and inflow No obvious benefits of previous pipe lining work 2

3 Flow, MGD Precipitation, inches 9/12/ Berlin Township WWTF Influent Flows and Precipitation mgd Inflow Infiltration /1/2007 7/20/2007 2/5/2008 8/23/2008 3/11/2009 9/27/2009 4/15/ /1/2010 Date precipitation Influent Flows Dry June Sewage, 2011 est 0.0 The Problems At a Glance High flows resulted in: Operational challenges at the WWTP TSS % removal violation (Feb/Mar/Apr 2009) Effluent ammonia violations (spring 2009) Operations staff storing excess water in the collection system to reduce permit violations Sanitary Sewer Overflow (March 2009) 3

4 Wastewater Flow (MGD) 9/12/2012 I/I Evaluation Analytical Review SRF Guidelines for dry sewage = 70 gpcd Berlin Twp has 3,600 sewer customers, or approx. 4,200 equivalent persons Dry sewage should be around 0.29 mgd Annual avg. flow was 0.66 mgd ( ) 0.84 mgd avg Mar/Apr/May = 201 gpcd, higher than 120 gpcd indicating excessive infiltration Sewer System Evaluation Survey Analytical review indicated both infiltration and inflow, presented some clues Purpose of the SSES was to identify specific sources of infiltration & inflow Total Wastewater Flow: St Charles Plus Lilly Patch Lift Stations /7/2011 3/21/2011 4/4/2011 4/18/2011 5/2/2011 5/16/2011 St Charles Lilly Patch WWTP Influent 4

5 SSES Setup / Approach Relatively large collection system for the number of sewer users (22.5 miles) Many smaller sewers feeding two main trunk sewers into the WWTP Needed cost effective way to do SSES Mass Monitoring covered nearly all of the 22.5 miles in one install! SSES Setup / Approach The old way of collecting SSES data Waiting for the stormflow 5

6 SSES Setup / Approach Mass Monitoring Inexpensive rental was $3/day per FloStick Easy installation no confined space entry Many data collection locations Image courtesy of FloCis Corp. SSES Setup / Approach Install mass monitor sensors in many key manholes in the system Data collected: Wastewater temperature Water depth Relative velocity (turbulence) Nearly continuous data collection! Every 5 minutes at each of 38 key manholes for 9 weeks!! 6

7 SSES Setup / Approach West District Divided into 13 Subdistricts SSES Setup / Approach East District - divided into 3 Subdistricts 7

8 SSES Results Mass monitoring allowed us to pinpoint which district(s) and subdistricts were contributing significant I/I Knowing sewer diameter, slope, and depth of water allowed us to estimate flow rates each storm Pump station data used to calibrate sewer flow rate estimates Able to differentiate inflow from infiltration with MM data Example Inflow Result FloStick #35, inflow indicated by increasing depth corresponding to decreased temperature Rainfall Depth Water Temp 8

9 Example Infiltration Result FloStick #12, depths remain high for a while after rain event and temperatures are relatively stable Rainfall Water Temp Depth Example Infiltration Result FloStick #20 Rainfall Depth 9

10 Surcharge/Storage Result FloStick #10, influent into the WWTP, shows 7.5ft of depth on 3/12/11 and 5+ ft several times in April Rainfall Depth SSES Summary of Results Vast majority of the flow is coming from the West District. Focus there. Large contributions of both inflow and infiltration in West District along Swan Creek. Large cold inflow volume at north boundary of West District (swampy area). Confirmed that the East District trunk, previously lined effectively with little infiltration detected, and minimal inflow in this low-lying area of concrete pipe 10

11 SSES Summary of Results Confirmed 10ft surcharge at the main trunk sewer during larger rain events Confirmed SSO relationship to trunk swer HWL, as operator uses collection system for storage SSO at manhole in East District was caused by hydraulic roadblock TDH, also backing up entire east district Prioritized key segments for improvements SSES Summary of Results SSO at manhole in East District was caused by hydraulic roadblock TDH, also backing up entire east district Sum of Lilly Patch Pump 1 Sum of Lilly Patch Pump Mo nth 11

12 SSES Summary of Results Ground-truthing Mass Monitoring System-wide smoke testing Televising of key sewer segments Confirmed results of SSES Estimate of each inflow source Deducted from estimate of I/I Swan Creek area 12

13 Ground-truthing Mass Monitoring Smoke testing Ground-truthing Mass Monitoring Smoke testing 13

14 Ground-truthing Mass Monitoring Smoke testing Ground-truthing Mass Monitoring Sewer televising 14

15 Ground-truthing Mass Monitoring Sewer televising Overall Result Prioritized rehabilitation plan Twp did not have to line entire lengths ($$) of large diameter trunk sewers Key manholes identified for rehab Expected $2.0M reduction in Project Cost from $6.75M => $4.7M 15

16 Status, Next Steps Job under construction 2012 Post-construction validation planned to measure amount of I/I removed & confirm that it meets Twp goal of ~40% removal Lessons Learned/Recommendations Use a few more flow meters Locate at key nodes in system to help calibrate Especially important if lift stations don t have easily accessible data Use an instantaneous type rain gauge Check the monitors/rain gauge regularly DEQ approval SSES methodology prior to implementation 16

17 Lessons Learned/Recommendations Use Mass Monitoring for other projects F&V is currently doing a similar project for Beecher Metropolitan District That project is going very well and study phase is funded through S2 Grant Questions? 17