Wet Weather Monitoring Program James Riddle Stormwater Management in Greenville County Greenville County, SC It All Flows Downhill: Land Use Water Quality Assessment

Wet Weather Monitoring Program Permit Requirements Per Permit Section II.B.10 Monitoring Program: The permittee shall develop a monitoring program to meet the requirements of Part V, (Monitoring and Reporting Requirements), of this permit.

Wet Weather Monitoring Program Permit Requirements After the inventory of major outfalls, delineation of the outfall catchment, and determining individual landuse contributions from each of those outfalls… Outfall Inventory Wet Weather Monitoring Develop EMCs Annual Loadings The County develops EMCs from the wet weather monitoring data to determine annual pollutant loadings to local receiving waters

Wet Weather Monitoring Program

Permit Requirements… by the numbers 5 - outfalls per permit year 5 - outfalls per permit year 3 - storm events/site 3 - storm events/site 72 - hours from previous event > 0.1 inches 72 - hours from previous event > 0.1 inches 1 – month between collected events 1 – month between collected events.23 - rainfall depth minimum depth requirement.23 - rainfall depth minimum depth requirement pollutants required for testing pollutants required for testing

Wet Weather Monitoring Program Monitoring Program Components 1. Equipment Selection 2. Site Selection 3. Sample Techniques 4. Flow Estimates 5. Program Oversight

Wet Weather Monitoring Program Equipment Selection American Sigma American Sigma 950 Flow Meter Meter w/bubbler level sensor Meter w/AV sensor 900 Max Sampler Tipping Bucket Rain Gage Insight Software   Communications Cellular communications unit Landline interface   20-Watt Solar Panel Equipment Selection

Wet Weather Monitoring Program Remote Communications Cellular Modems Cellular Modems Fairly Expensive Fairly Expensive Experiences Typical Cellular Phone Issues Experiences Typical Cellular Phone Issues Power Requirements Power Requirements Analog Analog Digital – requires GSM protocol Digital – requires GSM protocol Landline Interface Landline Interface Inexpensive Inexpensive Improved Reliabililty Improved Reliabililty No Power Requirements No Power Requirements Equipment Selection

Wet Weather Monitoring Program Site Selection Primary Siting Considerations Primary Siting Considerations Watershed (permit req.) Watershed (permit req.) Homogeneous Landuse (permit req.) Homogeneous Landuse (permit req.) Drainage Area Drainage Area Upstream Ponds Upstream Ponds Proximity to Office/Laboratory Proximity to Office/Laboratory Site Selection

Wet Weather Monitoring Program Site Selection Example Homogeneous Landuse – road runoff Homogeneous Landuse – road runoff Drainage Area Drainage Area Storm Sewer Connectivity Storm Sewer Connectivity Site Selection

Wet Weather Monitoring Program Site Selection Secondary Siting Considerations Secondary Siting Considerations Uniform Opening (ie. culvert) Uniform Opening (ie. culvert) Headwall/Wingwalls Headwall/Wingwalls Sedimentation Sedimentation Laminar Flow Laminar Flow Tree Cover Tree Cover Baseflow Depth Baseflow Depth Potential for Vandalism Potential for Vandalism Equipment Accessibility Equipment Accessibility Safety of Field Safety of FieldPersonnel Cellular/Landline Service Cellular/Landline Service Cooperative carriers Cooperative carriers Property Owner Property Owner Site Selection

Wet Weather Monitoring Program Site Selection Even more considerations… Even more considerations… Site Selection

Wet Weather Monitoring Program Sample Techniques $ Individual Bottle Sampling Appropriate for BMP testing or testing of specific parameter (ie. impairment) Appropriate for BMP testing or testing of specific parameter (ie. impairment) Pollutant concentrations throughout the event Pollutant concentrations throughout the event Composite Sampling Composite Sampling Sample Techniques

Wet Weather Monitoring – Sample Compositing Time OR Flow Weighted Composite Sample Techniques

Wet Weather Monitoring Program Sample Techniques $ Individual Bottle Sampling Appropriate for BMP testing or testing of specific parameter (ie. impairment) Appropriate for BMP testing or testing of specific parameter (ie. impairment) Pollutant concentrations throughout the event Pollutant concentrations throughout the event Composite Sampling Composite Sampling Appropriate for overall assessment or health of waterbody Appropriate for overall assessment or health of waterbody Average pollutant concentration Average pollutant concentration Sample volume QA/QC Sample volume QA/QC Sample Techniques * NPDES Phase I requirements necessitate full laboratory analysis using composite sampling

Wet Weather Monitoring Program Sample Techniques

Wet Weather Monitoring Program Flow Estimates Why do we need flowrate estimates? Why do we need flowrate estimates? 1. Flow-weighted composites 2. Mass loading estimates Flow Estimates

Wet Weather Monitoring Program Flow Estimates Ideal Approach Ideal Approach Use of primary device with known head versus flow relationship Use of primary device with known head versus flow relationship Use of secondary devices to determine flow depth Use of secondary devices to determine flow depth Flow Estimates

Wet Weather Monitoring Program Flow Estimates Secondary Devices Secondary Devices Examples include floats, ultrasonic sensors, pressure transducers, bubblers Examples include floats, ultrasonic sensors, pressure transducers, bubblers Provides depths and average velocities Provides depths and average velocities Data can be used in conjunction w/primary devices or w/more simplistic equations Data can be used in conjunction w/primary devices or w/more simplistic equations Flow Estimates

Wet Weather Monitoring Program Flow Estimates Ideal Approach Ideal Approach Use of primary device with known head vs flow relationship Use of primary device with known head vs flow relationship Use of secondary devices to determine flow depth Use of secondary devices to determine flow depth Common Approach Common Approach Use the Manning’s or continuity equation Use the Manning’s or continuity equation Use of secondary devices to determine flow depth and/or velocity Use of secondary devices to determine flow depth and/or velocity Flow Estimates

Wet Weather Monitoring Program Greenville County Flow Estimates Landuse Monitoring Landuse Monitoring Primary Device – develop head vs. flow relationships at culvert/bridges Primary Device – develop head vs. flow relationships at culvert/bridges Secondary Device – AV probes, bubbler tubes Secondary Device – AV probes, bubbler tubes Flow Estimates

Wet Weather Monitoring Program Program Oversight Equipment Operation & Maintenance Equipment Operation & Maintenance Diagnostics tests Diagnostics tests Power supply (ie. batteries) Power supply (ie. batteries) Modems Modems Vandalism Vandalism Program Oversight

Wet Weather Monitoring Program Program Oversight Equipment Operation & Maintenance Equipment Operation & Maintenance Diagnostics tests Diagnostics tests Power supply (ie. batteries) Power supply (ie. batteries) Modems Modems Vandalism Vandalism Vigilant Attention to Weather Vigilant Attention to Weather Minimum rainfall depths met Minimum rainfall depths met Adequate separation between events (permit req.) Adequate separation between events (permit req.) Don’t miss first flush, but be prepared for false starts Don’t miss first flush, but be prepared for false starts Roles- MS4 vs. Lab Roles- MS4 vs. Lab Program Oversight

Wet Weather Monitoring Program SFRIndustrialOfficeCommercialWoodsGolfRight-of-WayAverage Total Suspended Solids (TSS), mg/l Total Dissolved Solids (TDS), mg/l Bio-Chemical Oxygen Demand (BOD5), mg/l Chemical Oxygen Demand (COD), mg/l Total Phosphorous (TP), mg/l Dissolved Phosphorous (DP), mg/l Total Nitrogen (TKN + NO2 + NO3), mg/l Total Kjeldahl Nitrogen (TKN = NH3 + TON), mg/l Total Cadmium (TCD), mg/l Total Copper (TCU), mg/l Total Lead (TPB), mg/l Total Zinc (TZN), mg/l Current County EMCs

Wet Weather Monitoring Program

Current Status Completed final landuse monitoring this year Completed final landuse monitoring this year Comprehensive overall analysis in next annual report Comprehensive overall analysis in next annual report

Wet Weather Monitoring Program Other County Monitoring Projects BMP Performance BMP Performance Pelzer Pond – Detention Pond Pelzer Pond – Detention Pond Our Lady of the Rosary – Bio-Retention Cell Our Lady of the Rosary – Bio-Retention Cell Watershed Retrofit Study Watershed Retrofit Study Woodruff Road Woodruff Road

Wet Weather Monitoring Program Questions? James Riddle, PE Woolpert, Inc. Columbia, SC

Wet Weather Monitoring Program Monitoring Maxims Automatic samplers are not automatic… Automatic samplers are not automatic… After installing a sampler, it will only rain at night, on the weekends… After installing a sampler, it will only rain at night, on the weekends… Lab folks don’t understand hydrology… Lab folks don’t understand hydrology… Manning’s equation is not accurate for urban flows… Manning’s equation is not accurate for urban flows… TSS is a wastewater term… TSS is a wastewater term…

Wet Weather Monitoring Program

Sampling Sequence Triggers Wanted: Wanted: Samples Representative of Entire Runoff (or Outflow) Hydrograph Samples Representative of Entire Runoff (or Outflow) Hydrograph Sequence to Begin During Initial Washoff or First Flush Sequence to Begin During Initial Washoff or First Flush To Meet a Minimum Total Rainfall Depth To Meet a Minimum Total Rainfall Depth Sampling Sequence Triggers

Wet Weather Monitoring ProgramSampling Sequence Triggers

Wet Weather Monitoring Program Sampling Sequence Triggers Wanted: Wanted: Samples Representative of Entire Runoff (or Outflow) Hydrograph Samples Representative of Entire Runoff (or Outflow) Hydrograph Sequence to Begin During Initial Washoff or First Flush Sequence to Begin During Initial Washoff or First Flush To Meet a Minimum Total Rainfall Depth To Meet a Minimum Total Rainfall Depth Current Approach: Current Approach: Estimate Hydrologic Parameters Estimate Hydrologic Parameters Developed Triggers Unique for Each Station Developed Triggers Unique for Each Station Initiation of Sampling Sequence Initiation of Sampling Sequence Highly impervious watersheds – (ie. commercial, parking/roadways) Highly impervious watersheds – (ie. commercial, parking/roadways) Used rainfall trigger only due to erratic urban flows Used rainfall trigger only due to erratic urban flows Trigger much lower than required minimum rainfall depth, many false starts Trigger much lower than required minimum rainfall depth, many false starts Pervious watersheds Pervious watersheds Used rainfall and flow depth trigger Used rainfall and flow depth trigger Trigger sometimes greater than required minimum rainfall depth (NPDES req.) Trigger sometimes greater than required minimum rainfall depth (NPDES req.)

Wet Weather Monitoring Program Phase I Permit Requirements “…the Director shall designate between five and ten outfalls or field screening points as representative of the commercial, residential, and industrial land use activities…” (p ) “…the Director shall designate between five and ten outfalls or field screening points as representative of the commercial, residential, and industrial land use activities…” (p ) “…a flow-weighted composite (sample) shall be taken…” (p ) “…a flow-weighted composite (sample) shall be taken…” (p ) the sample “may be taken with a continuous sampler or as a combination of a minimum of three sample aliquots…” (p ) the sample “may be taken with a continuous sampler or as a combination of a minimum of three sample aliquots…” (p ) “…samples shall be collected of storm water discharges from three storm events occuring at least one month apart…” (p ) “…samples shall be collected of storm water discharges from three storm events occuring at least one month apart…” (p ) “…samples shall be collected… from a storm event that is greater than 0.1 inch and at least 72 hours from the previously measurable… storm event” (p ) “…samples shall be collected… from a storm event that is greater than 0.1 inch and at least 72 hours from the previously measurable… storm event” (p ) (Federal Register, Vol. 55 No. 222, November 16, 1990)

Wet Weather Monitoring Program Site Selection Another consideration… Another consideration… Site Selection