Okaloosa County BOCC — December 6, 2016 — Gap Creek QAPP — reading text

MS Matrix Spike MSD Matrix Spike Duplicate OPR Ongoing Precision and Recovery Precision, Accuracy, Representativeness, Completeness, Comparability PARCCS and Sensitivity QA Quality Assurance QAM Quality Assurance Manager QAPP Quality Assurance Project Plan QC Quality Control QCCS Quality Control Check Samples QL Quantitation Limits RPD Relative Percent Difference SOPs Standard Operating Procedures STEPL Spreadsheet Tool for the Estimation of Pollutant Load TKN Total Kjeldahl Nitrogen TSS Total Suspended Solids June 2016 | iii Gap Creek Stormwater Improvements Quality Assurance Project Plan Okaloosa County, Florida Distribution List Name Organization Address Phone Number Email Jason Okaloosa County 1759 South Ferdon Boulevard (850) 689-5772 jautrey@co.okaloosa.fl. Autrey, Engineer Crestview, Florida 32536 us Michael FL DEP Florida Department of (850) 245 2951 Michael.scheinkman@ Scheinkman, Nonpoint Source Environmental Protection dep.state.fl.us Management Division of Water Restoration Section Assistance Division of Water 3900 Commonwealth Blvd., Restoration MS 3570 Assistance Tallahassee, FL 32399-3000 Maria TestAmerica Inc. 3355 McLemore Drive, (850) 474-1001 Maria.bundy@ Bundy, Quality Pensacola, FL 32514 testamericainc.com Assurance Manager Brad Collins, HDR Engineering 25 West Cedar Street, (850)-429-8931 Michael.Collins@ Project Manager Suite 200 Hdrinc.Com Pensacola, FL 32502 iv |June 2016  Gap Creek Stormwater Improvements Quality Assurance Project Plan Okaloosa County, Florida 1 Introduction 1.1 Purpose This Quality Assurance Project Plan (QAPP) describes the procedures to be followed to achieve the objectives of sampling and analysis for the Gap Creek Stormwater Improvements in Okaloosa County, Florida. 1.2 Background The stormwater management system is located in the 2.9 square mile Gap Creek Drainage Basin, located in both unincorporated Okaloosa County and the City of Fort Walton Beach. Currently the system provides inadequate water quality treatment and flood attenuation. Most of this watershed is built out, primarily consisting of residential neighborhoods, multi-family, commercial and industrial uses. Runoff from portions of the basin receives little or no water quality treatment before discharging downstream into Gap Creek. A stormwater master plan was prepared by HDR Engineering in April 2003 and through modeling, the watershed has shown to have one of the highest pollutant loading rates in Okaloosa County. In 2008, in a cooperative effort between the Northwest Florida Water Management District, Okaloosa County and the City of Fort Walton Beach, the three agencies provided funding for a detailed water quality study of the Gap Creek watershed that was also completed by HDR Engineering. The purpose of this study was to identify and prioritize stormwater Best Management Practice (BMP) opportunities for enhancing treatment and pollutant loading reduction capability within the Gap Creek watershed. Of the 19 sites within the Gap Creek watershed recommended for retrofit opportunities to provide pollutant loading reduction, eight sites had also the potential to reduce flood risk in localized areas of the watershed. The structural BMP improvements for this project were chosen based on their high potential to provide both water quality improvements and flood attenuation. The original concept for this project included a treatment train within a 126 acre sub- basin of the Gap Creek watershed known as the Lovejoy Community. The project was comprised of modifying conveyance channels (upstream of Poplar Avenue Pond) to provide more storage and direct runoff to treatment areas, upgrading the existing County Poplar Avenue Pond to provide additional storage capacity and enhance nutrient uptake, and constructing a new stormwater facility (Echo Circle site) to provide additional treatment/attenuation and nutrient removal. The upgrades, as modeled by Spreadsheet Tool for the Estimation of Pollutant Load (STEPL), were expected to reduce nitrogen loads by 442 lbs/yr or 43.5%, phosphorus by 145 lbs/yr or 89.5%, Biochemical Oxygen Demand (BOD) by 3,400 lbs/yr or 91.2% and suspended sediment by 23.8 lbs/yr or 99.1%. Monitoring was planned for after completion of construction at the inflow and outflow of the proposed BMPs to determine the system’s effectiveness. Unfortunately, the project cannot be constructed as originally conceived thus requiring that the Grant Work Plan be amended. Only a limited amount of improvement to the conveyance to Poplar Pond was practical (a cross drain under Lovejoy Road is being June 2016 | 1 Gap Creek Stormwater Improvements Quality Assurance Project Plan Okaloosa County, Florida added and the pipe on the north side of Lovejoy Road that connects the roadside conveyance system to the pond is being replaced with an open channel). Some minor reconstruction of the berm for the existing Poplar Pond and modification of the outfall structure will also be done in the amended Gant Work Plan to maximize retention and detention. The other planned elements of the original treatment train were eliminated. Some of these original activities were not permittable, some were not necessary and some were simply found to be not practical during the design phase. The modeled estimated pollutant load reduction goals of the original project were very good and these results will not be achieved by the reduced scope of work. However, it is important to note that the water quality benefits of the conveyance improvements which were not part of the original modeled pollutant load reduction goals will still be achieved. By adding a culvert beneath Lovejoy Road and substantially increasing the capacity of the conveyance ditch to the existing Poplar retention basin and by replacing a pipe that was too small with an open channel we are now able to treat all of the stormwater runoff from the 86.9 acre watershed area up to a 25 year storm event and only 4% or less of the total annual runoff will bypass the treatment. What used to exceed the confines of the existing ditch and culvert system will now be properly conveyed allowing for much better treatment of the runoff. This will mitigate flooding potential and dramatically improve the total volume of water treated. ESTIMATED POLLUTANT LOAD REDUCTION: Analysis shows that for the existing condition, the annual total runoff for the 86.9 acre Poplar Pond watershed is 291.9 ac-ft. Flooding occurs above mean annual event, and about 32 ac-ft or 11 % of the annual total runoff is bypassed. After the improvements are made, flooding only occurs for events above the 25 year event. Only 4% of the total runoff will be bypassed or 11.6 ac-ft. Therefore, 20.6 ac-ft of runoff untreated in existing condition will be treated in the proposed condition. Using 1.2 mg/l TN, 0.26 mg/l TP and 65.2 mg/l TSS which are accepted as the EMCs for light industrial land use, the 20.6 acre feet being treated, and assuming 100% effectiveness for retention – approximately 66 lbs/yr, 14 lbs/yr and 3593 lbs/yr will be removed for TN, TP and TSS, respectively. 1.3 Goals The sampling and analysis described in this QAPP has the purpose of determining sample concentrations to determine the effectiveness of the BMP. Composite and grab samples will be collected from water flowing into and out of Poplar Pond. All sample analysis will be conducted by TestAmerica of Pensacola, Florida. To generate the intended data, it will be necessary to:  Collect stormwater and Quality Control (QC) samples in a manner consistent with QC goals  Package, label, and ship samples according to quality objectives  Coordinate with the laboratory for sample analysis and reporting  Maintain records of sampling and shipping activities  Verify that laboratory analysis meets quality objectives  Report sample analysis results to the client in three quarterly reports and one final report. 2 |June 2016  Gap Creek Stormwater Improvements Quality Assurance Project Plan Okaloosa County, Florida Data from each of the sampled storm event will be evaluated by comparing analytical results from the up-stream sample location (prior to entering into the BMP) to the analytical results as water leaves the BMP through the outlet structure. This comparison will determine the effectiveness of the BMP. These results can also be compared to national averages such as EMCs for similar wet pond BMPs to evaluate BMP effectiveness. 1.4 Organization Project team roles, responsibilities, and contact information is included on Table 1. The HDR Engineering Project manager will be responsible for coordinating with local HDR staff for the sampling event. This includes monitoring rainfall reports and oversight on sampling. The HDR Engineering Project manager will also coordinate with the project chemist to ensure laboratory requirements are met. The Lab QA manager will be responsible for coordinating with local Test America staff to conduct the proper analysis. Table 1. Key Roles and Responsibilities Name Role Organization Responsibilities Contact Information Brad Project HDR Project Management Michael.collins@hdrinc.com Collins Manager Engineering (850)-429-8931 Lynn Chemist HDR Analytical Review of Lynn.lutz@hdrinc.com Lutz Engineering laboratory data