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Utilities Department/Wastewater Division Standard Operating Procedure Procedure Name: C-10 Sanitary Sewer Spills Summary The City responds to SSSs and other sewer emergencies according to the Spill Emergency Response Plan (SERP). This plan describes the different components that make up the SERP. The SERP references several other SOPs including this one. Together they describe internal and external notification procedures, and spill response procedures. Effective Date Jan, 28 2014 Scope The purpose of this SOP is to provide specific guidelines for Sanitary Sewer Overflow (SSS) containment, clean-up, and spill volume estimation. This SOP does not include notification procedures. Guidelines/Authority SSS response and spill mitigation are required by the California State Water Resources Control Board Order WQ 2022-0103-DWQ Statewide Waste Discharge Requirements. These requirements and this SOP are incorporated in the City’s Sewer System Management Plan (SSMP). To Be Used By: This SOP is to be used by all Wastewater Division employees at the City of Modesto. Checklist/Procedures 1. GENERAL INSTRUCTIONS a. DON’T PANIC! b. When responding to an SSS, you need to work quickly to contain the spill, relieve the stoppage, and clean the spill. c. A supervisor or the manager should always be contacted and informed of the spill. In the event the spill reaches surface waters or is over 1,000 gals, a supervisor must be contacted as soon as possible. ---PAGE BREAK--- d. Remember pictures must be taken throughout the spill event and attached to the SSS record. Each SSS must include the following pictures: • Pictures and GPS of: 1. location where spill originated 2. If multiple appearance points, points closest to spill origin • Pictures of: 1. Extent of the spill spread 2. Location of spill cleanup 3. The following if applicable a. Drainage conveyance (storm) system entry points b. Discharge point into surface waters c. Waterbody bank erosion d. Floating matter e. Water surface sheen (potentially from oil or grease) f. Discoloration of receiving water g. Impact to the receiving water e. The on-site Customer Service operator or the main Standby operator is responsible for determining if an SSS is occurring, who is responsible for the SSS (the City, County, or a private party), and the completion of the following steps. 2. FIRST STEP – CONTAINMENT The first step is containment, if possible. Containment is not always possible or practical, but if it is practical, the operator should attempt to contain the spill. Note: during an active spill, the greater the volume of flow, the less likely containment will be practical. If containment is not practical, move to clearing the stoppage. Containment procedures include: a. Place rubber mats over catch basin or inlet b. Sandbag the gutter and/or catch basin, use sandbags and plastic sheeting c. Dig an earthen trench or build a berm d. Trace sewer flow within storm system. Follow sewer until non-contaminated water is observed. Use sandbags or dirt to build berm in pipe to contain flow. e. If the spill has reached a storm detention basin or pump station, contact the pump crew and turn off pumps (if possible). f. Take a picture of the spill appearance point, i.e. the maintenance hole or clean-out. 3. SECOND STEP – CLEAR THE STOPPAGE Depending on the volume of flow and the expectation of containment, this might be your first step. If containment is not the practical first step, after the stoppage has been cleared, attempt to contain any flowing sewage. To clear the stoppage, follow the procedures for clearing a stoppage contained within the Sewer Maintenance SOP. ---PAGE BREAK--- 4. THIRD STEP- ESTIMATE SPILL VOLUME After the stoppage has been relieved and before the clean-up begins, the first responder needs to estimate the spill volume that has been contained. This is performed by considering each area where sewage is contained separately, then adding the estimated amounts for each area. a. AREA ESTIMATION • Open the Spill Estimator app on your tablet and enter the required inputs to determine the spill volume. The methods below provide are used when manually computing spill volumes. • If the area is roughly square or rectangular estimate the volume by measuring the length and the width (in feet). Measure the depth in several places to obtain an average depth. For example: Depth Location Depth Measurement (in feet) Depth #1 .3 Depth #2 .5 Depth #3 .25 Depth #4 .75 Depth #5 .5 Average = Depth #1 + #2 + #3 + #4 + #5 Divided by the number of depth measurements (in this case 5) Average depth = .46 Volume = length X width X height Volume of a circle = diameter X diameter X .785 X depth ---PAGE BREAK--- Total spill volume in gallons = volume in cubic feet X 7.48 • If the area where the spill is contained is in the curb and gutter, you determine the spill volume by using the following formula; Volume in gals = length X width X average depth (obtained the same way as above) X 3.74 b. ESTIMATING SPILL VOLUME USING FLOW RATES • Spill volumes can be calculated based on observed flow rates. By observing overflowing maintenance holes and comparing to known overflow reference charts, the first responder can establish an estimated Gallon per Minute (GPM) overflow rate. Once the overflow rate is established, the operator simply needs to estimate the length of time the overflow occurred. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- 5. FOURTH STEP – CLEAN-UP SPILL a. SPILL IS FULLY CONTAINED • If the spill is fully contained, vacuum all sewage and wash down all hard surfaces and pipelines using potable water. • If the spill has been partially absorbed by soils, the soil should be removed and replaced as necessary and practical. • If the spill was contained within gravity storm pipelines, all water shall be removed and returned to the sewer. If there is too much water to vacuum, use pumps as necessary. • The total spill volume will be the volume recovered. b. SPILL IS DISCHARGED TO A ROCKWELL ---PAGE BREAK--- • If the spill is discharged to a rockwell, vacuum all debris from the rockwell and wash all surface areas with potable water. • The rockwell should be flushed with potable water. • If the spill discharged to a rockwell, calculate any spill volumes contained and recovered using the methods above. c. SPILL IS DISCHARGED TO A BASIN • If the spill is discharged to a basin, turn off all pumps (if any). • If spill occurs during a storm event and shutting off pumps will cause property damage, leave pumps on, but try to capture as much of the spill as possible. (Note: if spill is not fully contained within the storm basin, use discharged to surface water.) • If the basin contains a large volume of water, it may be necessary to use portable pumps to pump the water to the sewer. • All surface areas and pipelines shall be washed with potable water. • If the spill is contained within a basin and returned to sewer, i.e. the pumps were turned off and portable pumps were used to pump to sewer, the spill is considered fully contained and the volume recovered is equal to the volume spilled. When using this method it is important to use a generous amount of water to flush any pipes and the basin. d. SPILL IS DISCHARGED TO SURFACE WATER • If the spill is discharged to surface water, a supervisor or the manager must be contacted. • If the spill is discharged to surface water, an attempt should still be made to capture as much of the spill as possible. • All surface areas shall be rinsed with potable water while vacuuming to capture rinse water. • All pipelines shall be cleaned and vacuumed of any spill residue. • Clean-up crews shall work with Environmental Compliance to install public health warnings. • If the spill discharged to surface water, calculate any spill volumes contained on the surface or within a basin using the methods above, and subtract from volume spilled. 6. FIFTH STEP – COMPLETE SSS REPORT FORMS Once the spill has been cleaned-up, the SSS event must be documented. Within the Lucity Mobile App, locate the sanitary sewer line where the failure occurred. Using the selection tool (make sure you have right “Feature Type” selected), highlight the sewer line where the failure occurred. After the line is selected, click on the hardhat to create a work order. Fill-out the work order using the following codes: • Category – (if this is a mainline stoppage) or (if this is a private lateral stoppage) ---PAGE BREAK--- • Problem – SWCP70 Overflow or SWCP71 Overflow (Private) (if this was a private overflow) • Main Task – SWCT18 – Flush / Clean • Action Taken – 2 Cleaned/Cleared Then complete the remaining fields: • Assigned Crew • Senior Utility Worker • Operator in Charge • Findings • Any comments • Start and End dates and times Then save the work order. After the work order has been saved, open the red “toolbox”. Within the available tools and under the “Sewer” heading, click on “Create Sewer Overflow.” The overflow record will create in a ‘field’ view; click on the SSS record to open. These forms need to be filled in as completely as possible. When the SSS record has been filled out and saved, attach all before and after spill photos. Enter the SSS Status Enter the SSS location information This section is completed by the Customer Service or Standby person responding to call This section is completed by the Customer Service or Standby person responding to call ---PAGE BREAK--- OPEN SSS PACKET Open the SSS packet and follow the instructions and complete the SERP-2 form Field crews turn in the SSS Packet to the Senior USW assigned to sewer. 7. SIXTH STEP – OTHER SSS RESPONSE WORK ORDERS a. Stoppage Work Order Crews responding to SSSs will note the Stoppage by indicating the line segment of the stoppage and the “Primary” cause of the stoppage. b. Clean-up Work Order On a separate work order, crews will indicate the SSS clean-up by creating a work order for each Rockwell, storm maintenance hole, and storm line segments where clean-up activities were performed. Attachments <
- > Approving Authority/Revision Information SOP Sponsor Name: Robert Englent SOP Owner Name/Position: Robert Englent, Wastewater Collection System Superintendent Revision Date: August 23, 2023 Next Review/Revision Date: August 23, 2024