Stormwater Monitoring - Newington Solid Waste Facility
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This presentation focuses on the development of a monitoring program for a large-scale sand filter at the Newington Solid Waste Facility. The program was designed to both determine the efficiency of this best management practice and provide insight on the maintenance needs of such a facility.
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Stormwater Monitoring - Newington Solid Waste Facility
- 1. A Fairfax County, VA, publication Department of Public Works and Environmental Services Working for You! Stormwater Monitoring – Newington Solid Waste Facility Development of an Innovative Monitoring Program March, 2018
- 2. Newington Sand Filter Monitoring Project Development 2 • Site Selection • Design • Construction • Monitoring • Initial Findings • Lessons Learned
- 3. Newington Sand Filter Monitoring Site Selection • Project Considerations • County-wide evaluation – draft permit • Potential retrofit opportunity • 2+ impervious acres • High potential to discharge pollutants • Partnership with Solid Waste 3
- 4. Newington Sand Filter Monitoring Project Design – Sand Filter Specifications • Treats 2.30 Acres 4 • Treatment Volume: 7,728 CF• 60’ L x 18‘ W x 11’ H
- 5. Newington Sand Filter Monitoring Project Construction 5
- 6. Newington Sand Filter Monitoring Project Construction 6
- 7. Newington Sand Filter Monitoring Timeline • Construction Schedule – April 2015 – September 2015 • Filter Cleanout – Feb 2017 – Used coarser stones than initial installation 7
- 8. Newington Sand Filter Monitoring Monitoring Program Development • Monitoring Components • Establish objectives • Site-specific Considerations • Associated Partners • Parameter Suite • Sampling Design 8
- 9. Newington Sand Filter Monitoring Monitoring Program Development • Establish Objectives • Evaluate filter effectiveness at an industrialized site • Determine maintenance needs associated with a facility of this type and size • Site-Specific • Sample at inflow and outflow locations within sand filter • Identify Constraints • Location • Accessibility 9
- 10. Newington Sand Filter Monitoring Monitoring Program Development • Associated Partners • Facility Managers • Ingress/Egress, Safety Considerations • Maintenance Division • Responsible for design and upkeep • Design Consultants • Insight on monitoring locations • Monitoring Consultants • Responsible for data collection • Laboratory • Sample Analysis • Stormwater Planning • Oversight of sampling protocols and data analysis 10
- 11. Newington Sand Filter Monitoring Monitoring Program Development • Parameter Suite • Runoff from industrial site – parking area for waste disposal vehicles at end of shift • Characterize and quantify pollutant generation onsite • Comprehensive suite of analysis • Rainfall and Flow • Water Chemistry • Visual Indicators • Metals • Nutrients • Hydrocarbons 11 Parameter Total Rainfall Total Flow, cubic feet Composite cf ISCO 750 Area Peak Flow, cubic feet/second pH Conductivity Temperature Color Transparency Floating Matter Odor Sheen Biochemical Oxygen Demand (BOD5) Chemical Oxygen Demand (COD) Copper, Total Recoverable (Cu) Iron, Total Recoverable (Fe) Lead, Total Recoverable (Pb) Zinc, Total Recoverable (Zn) Total Kjeldahl Nitrogen (TKN) Nitrite - Nitrate (NO2-NO3) Total Nitrogen (N) Total Phosphorus (P) Total Suspended Solids (TSS) Total Petroleum Hydrocarbon - Diesel Range (TPH-DRO) Total Petroleum Hydrocarbon - Gasoline Range (TPH-TGO) Oil and Grease (O&G)
- 12. Newington Sand Filter Monitoring Monitoring Program Development • Sampling Design – Once per quarter over two years – Inflow (MS-1) and Outflow (MS-2) Autosampler Locations – Incorporate non-qualifying events in scope 12
- 13. Newington Sand Filter Monitoring Monitoring Program Development • Qualifying Storms • > 0.1 inches rain • Dry period of 72 hours • Composite Samples • Inflow and Outflow • Flow-weighted • Triggered by rain gauge and level • First flush Grab Samples • Hydrocarbons • Water chemistry 13
- 14. Newington Sand Filter Monitoring Initial Findings – Flow and Grab Samples • June 19, 2017: 0.15 inch rain event 14
- 15. Newington Sand Filter Monitoring Initial Findings – Event Mean Concentration (EMC) 15 • EMCs for Pre-Treatment (MS-1) and Post-Treatment (MS-2) • EMC – flow-weighted composite of a pollutant • NO2-NO3 increased, but total nitrogen decreased • Media Filters tend to remove organic nitrogen particulates and export nitrate
- 16. Newington Sand Filter Monitoring Initial Findings – Pollutant Loads • Pre-Treatment (MS-1) and Post-Treatment (MS-2) Pollutant Loads • Calculated by converting EMCs from mg/L to lb/cf and multiplying by total flow 16
- 17. Newington Sand Filter Initial Findings – Storm Event Summary • Total Flow reduced by 52% • Visual Indicators reduced • Temperature decreased • Effective at removing heavy organic materials • Significant reduction in most parameters • EMCs and Pollutant Loads • Attentuation and Lag Time • Grab sample complications • 1 hour and 40 minutes 17
- 18. Newington Sand Filter Lessons Learned - Sampling • Project Limitations • Limited Dataset • One successful storm event • Small storm • Potential impact on loading data • Two failed events • Not enough rain • Equipment malfunction • Collection Restraints • 72 hour dry period • Laboratory Hours • Facility Access • Safety Considerations 18
- 19. Newington Sand Filter Monitoring Lessons Learned - Maintenance • Maintenance Concerns 19 Size and use of the drainage area has an impact on loading time for the sand filter substrate. Filter clogged within a year Cleanout costs are high Increases significantly if clogging occurs deep into the sand layer. Maintenance is specialized Confined space entry Pump truck Experienced crew
- 20. Additional Information For additional information, please contact www.fairfaxcounty.gov/publicworks 20 Joseph Sanchirico 703-324-2548 joseph.sanchirico@fairfaxcounty.gov
Editor's Notes
- This discussion will focus on the development of a monitoring program for a large-scale sand filter at the Newington Solid Waste Facility. The program was designed to both determine the efficiency of this best management practice and provide insight on the maintenance needs of such a facility.
- I’ll go through the steps from concept to results, along with some lessons learned regarding both sampling and future maintenance of such a facility.
- This project was originally conceived in response to language in a draft MS4 permit. It stated that the County should identify facilities with greater than 2 acres of impervious surface with potential for stormwater retrofit opportunities. Based on a County-wide evaluation, the Newington Solid Waste facility had a high potential to discharge pollutants. In addition, the Director of Solid Waste was a very amenable partner and was willing to pilot new approached for managing stormwater.
- The primary focus of the retrofit was the development of a large-scale sand filter designed to treat runoff originating from a parking lot for approximately 60 waste disposal vehicles. The schematic give a sense of the dimenisons and the capacity of the filter. Designed to treat 1” of rainfall Drawdown time of 40 hours One quick, big rain activates overflow pipe
- Some photos to illustrate the scale of the project. ~$850,000 for construction of filter ~$85,00 for design costs
- Stormwater Planning was brought in to develop a monitoring plan. We’ll go through the steps that lead to actual sampling: Objectives Site Specific Considerations Partnerships Targeted Parameters Sampling Design
- An effective monitoring plan has to start with clearly defined objectives In this case, we wanted to: Evaluate BMP effectiveness at removing pollutants from stormwater runoff at an industrialized site Determine maintenance needs at such a facility – the County has experience with smaller-scale sand filters but this is the first we’ve installed at such an industrial facility at this size. We also need to take into account the location as we design the monitoring plan. - the filter has a defined input and output – targets for the autosamplers - safety considerations while sampling are important, as this is a high traffic facility with heavy equipment - BMP in a gated facility, so coordination is important
- Successful programs rely on coordination between invested parties. In this case, buy-in from the facility managers was critical to success, as disruption to regular activity while under construction is significant. Coordination with County maintenance staff was important as we learned more about the function of the sand filter Consultants who designed the facility could lend insight to the monitoring crew- in this case they were one and the same. A certified lab able to carry out the comprehensive sample analysis And the Planning team to ensure oversight and facilitation, in addition to long term data analysis
- To ensure we are capturing how efficient the BMP is, we developed a comprehensive parameter list for industrial sites. This includes flow, water chemistry, visiuals, metals, nutrients and hydrocarbons – the latter require a first flush grab sample, complicating sampling efforts.
- The intent of the sampling design is to collect one sample per quarter from both the inflow and the outflow of the sand filter. These photos show the two locations, and also illustrate the challenge in setting up monitoring locations.
- After setting up for a storm event, certain conditions need to be met to trigger a sample. Once the rain gauge measure > .1 inches of rain, the inflow autosampler will activate. As there is a lag for the water to travel through the filter, the outflow autosampler is triggered solely on level. As we are collecting hydrocarbons , they require a grab sample as well – this necessitates having staff on site during the event until both the infow and outflow samples are collected.
- At this point in time, we have only one successful event from last summer. I’d like to point out a few encouraging finds from this limited dataset: Total flow was reduced by 52 percent from inflow to outflow, which illustrates the ability of the sand filter to both slow down and attenuate the stormwater from the site. There was also a significant reduction in temperature after coming off the parking lot. For both the diesel-based hydrocarbons and the oil and grease parameters – almost 90% reductions were found . As we found during maintenance, the filter sludge smelled strongly of hydrocarbons, which is most likely byproduct from the trucks such as leaking hydraulic couplings and motor oil.
- EMCs decreased for all sampled parameters except for nitrate-nitrite. The literature shows that media filters tend to export this form of nitrogen, although the total N went down as a result of greater reduction of TKN.
- The decrease in total pollutant loads ranged from 53% for total nitrogen to greater than 87% for BOD5. It should be noted that the percent reduction of pollutant loads was greater than the percent reduction in EMCs. This can be attributed to the reduction in total flow measured at the outflow. A larger storm may not provide the same results as storage in the sand filter would be decreased, increasing the flow coming out.
- The influent flow was initially recorded at approximately 3:25 pm and measurable effluent flow began at approximately 5:05 pm resulting in a detention time of approximately 1 hour and 40 minutes. This variable increases the complexity for grab collection, necessitating staff remain on site during storm events for a long period of time.
- The results so far, while encouraging, are very limited. We have one successful storm, which was relatively low intensity. Two other events that we mobilized for were not successful – once for not enough rain and another for a clogged intake tube. As we move forward, we are considering revising the sampling protocol to increase chances for collection. Shortening the dry period to 48 hours and utilizing a lab with extended weekend hours would put more storms into play. Facility access and working in a busy facility are limiting factors that need to be taken into account as well.
- I also received some insight from maintenance staff – - an industrialized site such as this shortens the maintenance interval – scheduling for this type of facility will need to follow a different frequency than other sand filters in the County. It took about a year for the sand filter to fully clog after installation. Trash collection activities generate a higher than average amount of contaminated runoff. Maintenance could be cost prohibitive over the lifetime of the BMP Maintenance is specialized - The work must be conducted during a period or in such a manner where the extracted stone and sand will not be exposed to precipitation or runoff.