Under agreements totaling more than $4.5 million, KCI has and continues to provide stormwater quality monitoring and watershed planning services for the Delaware Department of Transportation. Tasks have included wet weather monitoring (WWM) of storm outfalls, conveyances, and best management practices (BMPs); and monitoring of streams impacted by stormwater discharges from BMPs, including sediment sampling and biological assessments. Tasks have included:
WET WEATHER BMP PERFORMANCE MONITORING STUDIES
Catch Basin Insert Performance Studies. At three different sites, our team installed 21 DrainPac, 8 HydroKleen and 19 UltraDrainguard catch basins and monitored their performance as BMPs. WWM of inlets protected by the inserts as well as inlets not protected was conducted. Sediment chambers were monitored to estimate the amount of sediment and other contaminants that the units prevented from entering the swale/ditch. Our team provided recommendations regarding future maintenance and installation of these units.
DelDOT I-95 Service Plaza BMP Performance Study. KCI evaluated the wet weather performance of the following BMPs at the I-95 Service: Delaware sand filter; bioretention swales; StormFilter; BaySaver; and HydroKleen AbTech Ultra-Urban, UltraDrainguard Catch Basin Inserts, and Suntree catch basin inserts. Scientists monitored the BMP influent and effluent, and estimated the hydraulic loading of the BMPs to determine pollutant removal capability. Our team conducted monthly field inspections of the BMPs at the service plaza to determine type and frequency of required maintenance, to facilitate future BMP recommendations.
DelDOT Maintenance Yard Monitoring. Our team completed three tasks at maintenance yards as part of DelDOT’s Individual Industrial NPDES permit:
- Semi-annual WWM at outfalls from 14 maintenance yards;
- Annual stormwater compliance inspections at 17 yards; and
- Street sweeper stockpile representative sampling to fulfill Delaware
- Solid Waste Authority requirements for landfill disposal. Samples are analyzed by a lab for a full Toxicity Characteristic Leaching Procedure and RCRA Analysis.
Wet Weather Monitoring Sampling Requirements & Opportunities. KCI conducts detailed storm tracking in advance of potential WWM sampling opportunities to ensure that sampling requirements are met. Each weekday morning, our team monitors weather conditions throughout Delaware and emails a daily weather report to NPDES staff at DelDOT and KCI. The daily weather data is compiled into monthly WWM storm tracking calendars, which are organized by DelDOT District. Each monthly calendar cross-referenced every WWM sample site with each day of the month, providing the following information: Valid, Invalid, Invalid (48 hours); Rainfall Events (predicted and actual amount); Site Sampled (yes/no); and the Reason (If No – rain was not forecast, insufficient rainfall, dangerous conditions).
Chapman Maintenance Yard Truck Wash Study. KCI has monitored truck wash operations at the Stormceptor/ Delaware Sand Filter unit at the Chapman Maintenance Yard since 2008. KCI completed a study evaluating the effectiveness of the Stormceptor/Delaware Sand Filter BMP train in reducing the sediment loading to nearby streams from maintenance yard truck wash operations.
Our experience showed most illicit discharges were found upstream of the outfall, so we have refined our screening to include contributing structures (i.e., inlet pipes, catch basins). This process has increased the number of illicit discharges found and eventually eliminated.
Bruce R. ThompsonSenior Project Manager and Environmental Scientist
GREEN TECHNOLOGIES AND BMP PERFORMANCE STUDIES
Median Mowing Study at Route 896. Scientists conducted WWM of two grassy areas on Route 896 that distribute flow to two separate inlets, to determine the impact that grass length has on stormwater runoff quality. The study included: Determining concentrations and loads of key pollutants in stormwater (for determining the potential of grass areas for use as a BMP); evaluating the effect that cut grass and uncut grass has on stormwater quality; and producing a report of findings for inclusion in the Annual NPDES Report.
Bioswale Study. KCI conducted WWM to evaluate the efficiency of a bioswale in pollutant removal and flow rate reduction for stormwater runoff.
Side Slope Study / Green Technology Modeling. Our team conducted a side slope study and developed a green technology model to quantify the total pollutant reduction of roadway runoff to grass medians and side slopes. KCI conducted WWM at a Route 299 side slope and developed a method for calculating the square footage of median and side slopes that receive highway runoff in New Castle County. The Route 299 WWM data was used to calibrate the model. The model focused on parameters: metals, nutrients, and total suspended solids; annual loading for Total Maximum Daily Loads (TMDL); and seasonal model runs, because seasonal environmental conditions (i.e., frozen ground, minimal winter vegetation) have the potential to impact infiltration and pollutant removal of grass swales.
Delaware Sand Filter Study. KCI completed a study that evaluated the functionality of the stormwater management device known as the Delaware Sand Filter (DSF). Activities included DSF sample site selection, developing a study approach, dry and wet weather observations, collecting sand samples for laboratory analysis, critiquing the study methodologies, identifying initial maintenance recommendations, installing automated wet weather sampling at the Wilmington DTC DSF, and developing a detailed maintenance schedule for the Lancaster Pike DSFs.
KCI began annual inspections of each numbered DelDOT DSF, by incorporating protocol developed from the DSF Study.
ILLICIT DISCHARGE DETECTION AND ELIMINATION (IDDE) PROGRAM
KCI conducts dry weather screening/inventory and illicit discharge detection of DelDOT-owned storm drain outfalls. Our responsibilities include DelDOT-owned municipal separate storm sewer system (MS4) outfall evaluation; dry weather outfall field screening; potential illicit discharge (PID) investigations, NPDES door hanger distribution, data input to DelDOT’s NPDES IDDE field screening website; and STOPPIT hotline field investigations. Since beginning this work in 2006, scientists have investigated hundreds of Potential Illicit Discharges (PIDs) and distributed more than 1,200 NPDES awareness flyers.
Outfall Drainage Areas/BMP Drainage Areas. Using the NPDES database created by KCI, our team continued to update drainage areas for DelDOT-owned major outfalls and DelDOT-owned BMPs throughout the state. In addition, scientists provided an annual submission to DNREC that contained information such as drainage area, BMP type, etc., for use in the Chesapeake Bay Program to receive credit toward meeting the goals of the Chesapeake Bay nutrient and sediment TMDLs.
South Bethany Storm System Study. KCI mapped the storm sewer in South Bethany and conducted screening to determine primary pollutant sources, as part of a broader study of the Anchorage Canal drainage area by the Center for Inland Bays. In 2009, a sediment sample was collected from the Anchorage Canal sediment forebay and analyzed for hazardous substances, to evaluate its suitability for disposal at a Delaware Solid Waste Authority landfill.