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HomeMy WebLinkAboutSW3220201_Stormwater Narrative_20220419Frank Liske Park Barn Concord, North Carolina Proiect Description Location This project involves the construction of a new building, as well as new hardscape and water service to replace the barn previously burned down at this location. Project construction will take place on tax parcels 55291135040000, which contain 653.78 acres. The current property owner is the State of North Carolina, but is currently being transferred to Cabarrus County, and will be the financially responsible party. The disturbed area is approximately 3.1 acres. Topography/Drainage Parcel 55291135040000 is currently developed as a county park and houses a variety of attractions. These include, multiple sports fields, walking trails, playground areas, a park office and a miniature golf course. Generally, this site drains to the lake and several ponds on the property. The portion of interest in this project, is located on the high point of the park and sheet drains in all 4 directions away from the previous barn location. While four small area drains are being added to this location, this is simply to divert storm water away from the proposed building. All pipe sizing was done according to the 2018 NC Plumbing Code (See drainage area map for table). Rip rap calculation were performed for the outlet for these drains. With a discharge velocity of less than 2 feet per second, rip rap was not deemed necessary. These calculations can be found in section 2 of this report. While there are several storm pipes and area drains, these conveyances are simply to move water away from the building and serve as extension to the roof drains. The area these drains serve, collect rainfall from the hilled area just north of the proposed barn. The site was designed with the intention to avoid cutting down several 24+ inch diameter old growth trees. In addition, the previous barn structure had a similar system in place that directed the roof drain water underground (from the east side of the barn), into a collector drain, and discharged into a small rip rap section on the west side of the barn (see picture below). The area drains and pipes in this design are intended to provide a similar drainage pattern to the one that existed previously and replace it in kind. The discharge for these pipes is located adjacent to the building and release all stormwater onto a vegetative hill that then sheet drains within the property. No stormwater impacts to the property are anticipated as part of this project. Soi is The soil survey of Davidson County indicates soils on the site are as follows: • Chewacla Sandy Loam - ChA (0 to 2% slopes) (Class B/D) • Iredell Loam - IdA (0 to 2% slope) (Class C/D) • Mecklenburg Loam - MeB (2 to 8% slope) (Class C) Frank Liske Park Barn Concord, North Carolina Erosion Control Plan The erosion control and sedimentation measures included in the plan are gravel construction entrance, temporary skimmer basin, silt fence, erosion control matting, seeding and mulching. Erosion control of the site is being controlled by sheet draining into two separate temporary skimmer basins. Areas not caught by sheet flow will be caught by a diversion Swale and channeled to the basins. The diversion ditches and basin slopes shall be immediately matted and temporarily seeded. Due to the existing topography, the project area, and portions of the project where only water line is being installed, will be managed by small drainage areas terminating with silt fence and stone lined openings. These areas a very small and are anticipated to received very little storm water. Pictures Previous drain discharge. Old growth trees to be preserved Drainage Area Map Refer to the drainage area maps in the appendix section of this report.