A Systematic Approach to Reduce Infiltration and Inflow (I&I) and Sanitary Sewer Overflows (SSO) PETE GORHAM, P.E. MIKE LYNN FEBRUARY 19, 2015

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1 A Systematic Approach to Reduce Infiltration and Inflow (I&I) and Sanitary Sewer Overflows (SSO) PETE GORHAM, P.E. MIKE LYNN FEBRUARY 19, 2015

2 Infiltration/Inflow (I/I)

3 I & I Reduction: Three-Prong Attack Large Drainage Basin Sanitary Sewer Evaluation Survey (SSES) Find and Fix Rehabilitation Program Small Drainage Basin Flow Monitoring

4 Large Drainage Basin SSES Effort began in 2006 due to sewer flow metering results from RWSA Comprehensive Sanitary Sewer Interceptor Study. Utilized term contract consultant to conduct SSES in 5 priority drainage basins. Entered into Consent Order with Department of Environmental Quality (DEQ) in 2010 that incorporated ACSA plan for the priority basins.

5 Background of the Consent Order In 2006, all 3 Utilities began focusing efforts on evaluating the condition of the existing sewer infrastructure. Warning Letter from DEQ issued to the ACSA on April 21, 2010 in response to unpermitted discharges in the table below. Consent Order adopted by ACSA on March 17, Goals of the Consent Order: Ensure adequate capacity for existing and future flows. Eliminate sanitary sewer overflows. Reduce Infiltration and Inflow (I/I) in the sanitary sewer system. ACSA Unpermitted Discharges Date Cause of Overflow Impacted Waters November 17, 2008 Loss of 3-Phase Power to Pump Station Rivanna River April 27, 2009 Grease Blockage unnamed creek June 22, 2009 Grease Blockage Carroll Creek

6 DEQ Consent Order Status Rehabilitation of the public sanitary sewer system is complete in 4 of 5 priority drainage basins. Rehabilitation of the Farmington private sanitary sewer system is budgeted, schedule is pending (Ednam Drainage Basin). SSES Report is being finalized for the last priority basin: PVCC Drainage Basin. Rehabilitation of PVCC Drainage Basin scheduled to begin spring This will complete the Consent Order.

7 Find and Fix I&I Reduction Program Coordinated effort between Maintenance and Engineering staff. Closed circuit television (CCTV) vans target older sewer mains, especially terra cotta (clay) mains. CCTV footage provided to engineer for evaluation of defects and prioritization of work. Engineering develops spreadsheet estimating cost of rehabilitation work and issues work order under piggyback of City s Miscellaneous Sewer Rehabilitation Contract.

8 Closed Circuit Televising The ACSA has two CCTV vans. They are deployed into the ACSA jurisdictional area daily to gather information regarding: Line condition Grease build-up Line obstructions Defects in pipes Line breaches Proper installation of new pipe

9 Types of Manhole Rehabilitation Before After

10 Relining, Pipe Bursting, Replacement Clockwise (from top left): CIPP Relining, Point Repair, Complete Replacement, Pipe Bursting

11 Total Rehabilitation Project Expenses Drainage Basin Study Cost Rehabilitation Cost Meadow Creek $417,707 $2,001,236 Crozet Phase 1 $134,637 $54,495 Scottsville $84,545 $37,873 Crozet Phase 2 $181,818 $99,020 Biscuit Run $176,112 $63,309 Woodbrook $130,641 $253,088 FY 2012 Miscellaneous Find and Fix $414,650 FY 2013 Miscellaneous Find and Fix $631,807 Ednam $81,007 $37,175 PVCC $94,000 $120,900** FY 2014 Miscellaneous Find and Fix $435,748 FY 2015 Miscellaneous Find and Fix $400,000** TOTALS $1,300,467 $4,549,301 ** Budget Amount

12 Small Drainage Basin Flow Monitoring Flow Meters installed in strategic locations to isolate sections of the drainage basin and collect flow data. Rain Gauges installed in the area to collect rainfall data. Wastewater Flow Components are collected from the flow meter: Average Daily Flow (Dry Weather) Peak Daily Flow (Dry Weather) Peak Wet Weather Flow Dual Purpose: Identify drainage basins with I&I problems and gather data for Wastewater Hydraulic Model Calibration

13 Sanitary Sewer Overflow Reduction Program Every SSO is reported to DEQ within 24 hours. Preventative maintenance is carried out through a regular schedule of rodding and flushing. CCTV vans identify pipes not flowing properly due to roots and grease. They are added to the rodding and flushing schedule. Upgrading wastewater pump stations. Fats, Oils and Grease (FOG) Reduction Program. Maintenance estimates grease is involved in approximately 70% of all SSO s.

14 Sanitary Sewer Overflows (SSO) Fiscal Year No. of SSOs

15 Sewer Main Rodding & Flushing

16 CCTV Inspection Pictures Root Intrusion & Cracks Grease In Line

17 Upgrading Wastewater Pump Stations Equipment and power failures at pump stations can produce SSO s. All 12 wastewater pump stations have an emergency bypass connection and Maintenance has two portable emergency bypass pumps. Standby generators have been installed at 8 of the 12 wastewater pump stations.

18 Fats, Oils and Grease (FOG) Reduction Program All food service establishments (FSE) are required to have permits detailing their grease control devices. Unannounced inspection visits to ensure grease control devices are being properly maintained. If CCTV vans discover a grease issue, they attempt to pinpoint the source. If successful, our Environmental Group is notified to proceed with enforcement of ACSA Rules & Regulations. An education program has been established for residential customers utilizing radio and print media, as well as, direct delivery of FOG Education Kits.

19 Future Action Items RWSA Comprehensive Sanitary Sewer Interceptor Model Update for the Wastewater Cost Allocation Agreement: Reveal where improvements have reduced I&I. Give direction to next priority drainage basins. Methodically transfer routine rodding & flushing locations to the rehab/repair/replacement program Utilize the SCADA system to track wastewater pump stations operational data: Pump Station discharge rates during dry & wet weather. Identify sub-drainage basins where I&I needs to be reduced. Add large drainage basins for SSES work to the CIP Budget (3 added in current proposal). Utilize a calibrated Wastewater Hydraulic Model to project impact of wet weather events on system capacity.

20 Any Questions?