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Home My WebLink About20201835 Ver 1_Pre-Filing Meeting Request_20201130ID#* 20201835 Version* 1 Regional Office* Wilmington Regional Office - (910) 796-7215 Reviewer List* Robb Mairs Pre -Filing Meeting Request submitted 11/30/2020 Contact Name* Contact Email Address* Project Name* Project Owner* Project County* Owner Address: Dawn York dyork@moffattnichol.com Reduction of Nutrient Loading to Greenfield Lake from Jumping Run Branch, Wilmington, North Carolina, Phase I Cape Fear River Watch New Hanover Street Address 617 Surrey Street Address Line 2 City Wilmington Fbstal / Zip Code 28401 Is this a transportation project?* (- Yes o No Type(s) of approval sought from the DWR: 141 401 Water Quality Certification - 1— 401 Water Quality Certification - Regular Express I— Individual Permit I— Modification I— Shoreline Stabilization Does this project have an existing project ID#?* C Yes (-- No State / Rovince / Fbgion NC Country USA Do you know the name of the staff member you would like to request a meeting with? Please give a brief project description below.* Greenfield Lake, in urban Wilmington, N.C. suffers from green and blue-green algal blooms (Vander Borgh 2014), bottom -water hypoxia, fish kills, and high fecal coliform bacterial counts. The lake was placed on the NC 303(d) list in 2014 for excessive chlorophyll a. Mallin et. al. (2016) from UNC Wilmington detailed the lake's eutrophication and poor water quality and determined that nhvtnnlanktnn arowth in the lake was hinhly stimulated by nitrnnen (N) inputs. However, blooms of the N-fixing cyanobacterium Anabaena dominate in summer (a N-fixing species basically captures its own N if enough phosphorus (P) is present). Thus, phosphorus is also important in driving the lake's eutrophication. A 2018 M.S. thesis by Nick Iraola of the UNC Wilmington Center for Marine Sciences determined that two of the five perennial streams feeding the lake, Jumping Run Branch and Squash Branch, provided the vast majority of stream -derived inorganic N and P to the lake. As such, a consortium of stakeholders (City of Wilmington, Cape Fear River Watch, UNCW, NC State University and Moffatt & Nichol) received funds from the DEQ 319 program to reduce nutrient loading from Jumping Run Branch to the lake to curb eutrophication through reduced nutrient inputs, lower chlorophyll a concentrations, and an improved lake ecosystem. These efforts will eventually lead to the removal of the lake from the 303(d) list. This effort is coordinated by Ms. Dana Sargent of Cape Fear River Watch, a non-profit that currently manages the Greenfield Lake Boathouse through a contract with the City of Wilmington, and conducts environmental education activities, ecotours, and clean-ups in Greenfield Lake and its tributaries. This proposed project focuses on improvements in nutrient reduction to Jumping Run Branch as the City of Wilmington owns land along its path and is a partner in this proposal, providing ongoing maintenance as well as access and permission to modify the property. The first phase of the project, and the subject of this pre -filing notification, includes the modification of two existing impoundments in Jumping Run Branch (Willard Street upper and lower wet ponds) to improve pollutant removal performance; management of existing vegetation; retrofit of an existing wet pond by installing improved riser structures to extend detention time and extensive monitoring and assessment in key locations by UNCW researchers to quantity the effects on water quality and denitrification process; providing environmental education and outreach to local residents. Neither impoundment currently has a riser or similar outlet control structure. Both have piped outlets that create minimal detention time according to preliminary hydrologic and hydraulic (H&H) analyses. A riser structure would be added to both to increase detention time substantially and improve removal of a variety of pollutants. The upper impoundment (Figures 1 and 2) has areas of shallow open water that direct runoff along a short path to the outlet, along with higher areas that appear to be infrequently inundated. A substantial amount of scour was also observed within the cell. Likely through two phases of construction, this cell will be regraded to incorporate new inlet pools for energy dissipation, create longer flow paths, excavate high zones to convert them to wetland and add storage volume, make portions of the open water area shallower to create wetland, and plant the new wetland zones. A United States Army Corps of Engineers (USACE) Nationwide Permit (NWP) 43 is applicable as the project consists of conducting maintenance of a stormwater management facility and incorporating pollutant reduction green infrastructure features. The project will not expand the existing footprint of the stormwater ponds, but will include some grading, with possible new native planting and the addition of risers. Please give a couple of dates you are available for a meeting. 12/8/2020 12/9/2020 12/11 /2020 Please attach the documentation you would like to have the meeting about. Jumping Run Branch Project Components 241.32KB Annotated.pdf Jumping Run Branch Vicinity Map.pdf 281.97KB Project Progress Update_102020.pdf 1.06MB pdf only By digitally signing below, I certify that I have read and understood that per the Federal Clean Water Act Section 401 Certification Rule the following statements: • This form completes the requirement of the Pre -Filing Meeting Request in the Clean Water Act Section 401 Certification Rule. • I understand by signing this form that I cannot submit my application until 30 calendar days after this pre -filing meeting request. • I also understand that DWR is not required to respond or grant the meeting request. Your project's thirty -day clock started upon receipt of this application. You will receive notification regarding meeting location and time if a meeting is necessary. You will receive notification when the thirty -day clock has expired, and you can submit an application. Signature Submittal Date 11/30/2020 a�SR►E river _ I I � - yrOdS�ER S7 � � J j� }AYiSa�t 5'� Li PROJECT LOCATION �L' 5 u I VICINITY MAP wT4 Jumping Run Branch Nutrient Loading Reduction Project Team Meeting and Request for Feedback Date 10/21/2020 Project Scope Overall Project Goal: increase storage/retention time in Willard St. wetland upstream of Jumping Run Branch to improve pollutant removal prior to discharge to Greenfield Lake •Data Collection –City GIS data, land cover/soils, site topographic survey •H&H Modeling –existing conditions and design conditions •Design –outlet control structure, pond grading, planting and vegetative management planning •Construction Documents –construction plans, technical specifications, bid documents •Permitting –401/404 Existing Site Topographic Survey WithersRavenel Existing Conditions XPSWMM Model •Drainage areas delineated to each inlet pipe •Hydrologic parameters calculated using City GIS, land use, and soils data •Upper and lower pond stage- storage relationships developed using topographic survey •Connecting culverts and earth berms modeled •Water quality event (1.5-inch) and 2-, 5-, 10-, 25-, 50-, and 100-year design storm events modeled 10.4 10.45 10.5 10.55 10.6 10.65 10.7 10.75 10.8 1/1/2021 0:00 1/2/2021 0:00 1/3/2021 0:00 1/4/2021 0:00Water Surface Elevation (ft)Date Existing Conditions Model Results Drawdown time: 35 hours Water Surface Elevation in Upper Pond Design Conditions XPSWMM Model •Riser structure designed to retain runoff from 1.5-inch water quality event •2” orifice on riser structure •No additional flooding created upstream of inlet pipes during design storm events Existing CulvertExisting Berm Lower Pond Proposed Riser Structure Upper Pond 10.3 10.5 10.7 10.9 11.1 11.3 11.5 11.7 1/1/2021 0:00 1/2/2021 0:00 1/3/2021 0:00 1/4/2021 0:00 1/5/2021 0:00 1/6/2021 0:00Water Surface Elevation (ft)Date Design Conditions Model Results Drawdown time: 96 hours Water Surface Elevation in Upper Pond Progress to Date Data Collection (May –September 2020) H&H Modeling –existing conditions and design conditions (September –October 2020) •Design – Outlet control structure (October 2020) •Pond grading, planting and vegetative management planning (October –November 2020) •Construction Documents (October –November 2020) •Permitting (November 2020) Next Steps •Design –Pond grading, planting and vegetative management planning (November 2020) •Final Design Team Progress Meeting (November 2020) •Agency On-Site Meeting (early December 2020) •Submit Permit Applications (December 2020) •Preliminary Construction Documents (December 2020)