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Home My WebLink About20190020 Ver 1_Cover Letter_20190109-40 WithersRavenel NOOur People. Your Success. January 9, 2019 US Army Corps of Engineers NC -Division of Water Resources Wilmington Regulatory Field Office 401 & Buffer Permitting Unit Ms. Rachel Capito Ms. Karen Higgins 69 Darlington Ave 1617 Mail Service Center Wilmington, NC 28403 Raleigh, NC 27699 Re: Loblolly Landing Subdivision - NWP 18 PCN Submittal (Revised) Wilmington, New Hanover County USACE AID#: SAW -2017-01889 WR Project #03170198.01 Dear Ms. Capito and Ms. Higgins, On behalf of Pompano Development Group, LLC, we are requesting authorization from the USACE to use NWP 18 for 0.031 acres of permanent wetland impacts for construction of the proposed project. The proposed impacts do not meet the conditions in WQCG NO. 4139 for requiring written authorization from NCDWR and therefore, this is being provided to NCDWR as a courtesy. The project is ±4.23 acres in size and is located at 7312 Mason Landing Road in Wilmington, New Hanover County (Latitude: 34.265917°N; Longitude: -77.777660°W). The project is located in the White Oak River basin and onsite waters drain to Pages Creek. The Water Quality Classification for Pages Creek is SA;HQW and the Stream Index Number is: 18-87-21. The cataloging unit for the site is 03020302. Proposed Proiect The purpose of the proposed project is to construct an access road and stormwater infrastructure to facilitate construction of an 8 -lot residential subdivision to meet the current demand for single family residential houses in northern New Hanover County. The proposed project consists of the construction of the proposed subdivision, access road and infrastructure (stormwater, water, sewer, etc). The proposed impacts will occur from construction of the access road from Mason Landing Road, as well as construction of the outlets of two vegetated stormwater swales. The construction of the access road will result in 0.007 acres of permanent wetland impacts (Impact 2). The impacts are necessary to grade the slopes of the road fill to natural grade. The onsite stormwater management system consists of three vegetated stormwater swales, which will provide water quality treatment for the subdivision. The stormwater management system has been designed to direct the majority of the treated runoff into the onsite wetland, thereby maintaining and even improving its hydrology, ensuring the wetland will remain a wetland in perpetuity. The construction of two of the vegetated stormwater swales will result in 0.024 acres 219 Station Road, Suite 1011 Wilmington, NC 28405 t: 910.256.9277 1 www.withersravenel.com I License No. C-0832 Asheville I Cary I Greensboro I Pittsboro I Raleigh I Wilmington Loblolly Landing Subdivision - NWP 18 PCN Submittal %0 WithersRavenel lipOw People. Your Success. of permanent wetland impacts (Impacts 1 & 3). The impacts will result from construction of portions of the vegetated swales within the wetlands, as well as the check dams and rip -rap pads to reduce flow velocity and prevent erosion within the wetland. The vegetated stormwater swales must extend into the wetland in order to meet the minimum 100 -ft length as required by the stormwater SCM manual, and therefore cannot be shortened to avoid the wetland impacts. However, the benefit to the wetland from receiving the treated runoff exceeds the loss of function from the 0.024 acres of permanent wetland impacts from construction of the stormwater swales. Standard commercial construction equipment and techniques will be used to construct the proposed project. Please note that we are requesting authorization of the proposed impacts under a NWP 18. NWP 29 Additional Regional Condition 4.1.1 prohibits discharges into wetlands for stormwater management facilities. Therefore, we are requesting a NWP 18 because impacts to wetlands for stormwater management facilities are not prohibited under a NWP 18. Project History The US Army Corps of Engineers (USACE) issued an Approved Jurisdictional Determination (SAW - 2017 -01889) for the project area on 10/5/2017. A copy of the Jurisdictional Determination has been provided as an Appendix. Proposed Impacts The proposed impacts consist of 0.031 acres of permanent wetland impacts. The proposed 0.024 acres of permanent wetland impacts (Impact #1 & 3) are for the construction of two vegetated stormwater swales, a check dam and rip -rap dissipation pad. The proposed 0.007 acres of permanent wetland impacts (Impact #2) are from grading necessary for the construction of the proposed access road. Avoidance and Minimization Prior to site plan design, the applicant requested that a detailed wetland delineation be conducted so that impacts to wetlands and "waters" could be minimized. Due to the size and location of wetlands on the site, impacts to wetlands could not be avoided but were minimized to the maximum extent possible. Wetland impacts for construction of the vegetated stormwater swales (Impact #1 & 3) were minimized by designing them to meet the minimum requirements of the stormwater SCM manual. Additionally, the proposed swales were designed in an "L -shape" in order to utilize as much uplands as possible to meet the minimum 100 -ft length requirement before entering the wetland. In the existing condition, a ditch runs through the onsite wetland which drains to the northern property line, then west where it eventually flows into an existing culvert under Mason Landing Page 2 of 4 Loblolly Landing Subdivision - NWP 18 PCN Submittal %0 WithersRavenel lipOur People. Your 5ucce55. Road. This ditch has altered the hydrology of the wetland. The stormwater management system has been designed to maintain and improve the hydrology within the wetland by conveying treated runoff into the wetland through vegetated stormwater swales. The swales will discharge treated runoff into the outer edges of the wetland, allowing for infiltration of surface flow before reaching the ditch. By conveying the treated runoff to the wetland, they hydrology of the wetland will be maintained in the post -development condition, which will ensure that the wetland continues to function as a wetland in perpetuity. If the runoff from the development was bypassed around the wetland into the downstream portion of the ditch, the wetland would eventually dry up and eventually cease to be a wetland. Therefore, proposed wetland impacts for construction of the vegetated stormwater swales provide a hydrologic benefit that exceeds the functional loss of the proposed 0.024 acres of permanent wetland impacts from the vegetated stormwater swales. Wetland impacts from construction of the access road were minimized to only those necessary for the backslopes necessary to grade road fill to existing grade. The access road was aligned to avoid the onsite wetland as much as possible, while meeting minimum curve radii. Register Lane, located along the southern property boundary, is a private road, and could not be utilized for access to the proposed subdivision. Silt fencing will be installed around all disturbed areas to prevent sediment from escaping into wetlands during construction. During construction, all equipment will access construction areas from high ground. Mitigation The proposed project will result in less than 0.10 acres of permanent wetland impacts and therefore, the applicant does not propose mitigation. Stormwater Management Plan The stormwater management plan consists of a combination of grassed swales, check dams and rip -rap dissipation pads. The stormwater management plan will be reviewed and approved by New Hanover County and NCDEQ Coastal Stormwater Program. The current request is for 0.031 acres of permanent wetland impacts (see the attached maps and PCN for details). Please feel free to call if you have questions or require additional information. Sincerely, WithersRavenel Troy Beasley Page 3 of 4 Loblolly Landing Subdivision - NWP 18 PCN Submittal Senior Environmental Scientist Attachments: • PCN Form • Agent Authorization • Wetland Exhibit • USGS Quad Exhibit • New Hanover County Soil Survey Exhibit • Approved Jurisdictional Determination • USFWS List - New Hanover County • NCNHP Letter • Impact Exhibits :: WithersRavenel Dur People. Your Success. Page 4 of 4