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HomeMy WebLinkAboutNCC230818_MODIFICATION Supporting Documents_20240422 (3) M73 Cardinal to NC State Pipeline Project Dominion Energy Raleigh, North Carolina Erosion and Sediment Control Narrative Project Scope: This narrative is intended to supplement the Notification Form being resubmitted for the installation of the M73 Cardinal to NC State natural gas pipeline in Raleigh, North Carolina by Dominion Energy (Dominion) in Wake County. The proposed project includes installation via a combination of open trench and horizontal directional drill (HDD) methods of approximately 55,820 linear feet of 12-inch steel natural gas pipeline. The pipeline area generally encompasses the area between the southern edge of the road right of way (ROW) and the northern edge of the first traffic lane, and the replacement of the natural gas regulator station falls within the private easement on the south end of the pipeline. The attached erosion and sediment control plans provide a summary of the work, including best management practices. Due to the small linear work areas proposed and limited amount of earthwork, proposed erosion and sediment control measures for this project include perimeter compost filter socks and silt fencing at the edge of private landowner parcels, or easements, and erosion control blankets within an existing grass lined swale and proposed station slopes to facilitate access and work within the right-of-way. The project area falls within the Upper Neuse River basin. There are floodplains within the existing natural gas pipeline portion of the project, however there will be no excavation or grade change within the floodplain. There are no floodplains within the proposed regulator station area. Note that there will be no change in impervious surface area from pre-to post-development conditions throughout the pipeline installation portion of the project. The regulation station development portion of the project is small and has a Built Upon Area (BUA) of 1.1%, well below the thresholds for a low-density development area. Disturbed areas will be stabilized sequentially as construction proceeds within the proposed limits of disturbance. Access improvement, including the clearing of trees, will take place, however, clearing will be outside of the tree conservations areas. Excavation generated by installation of underground facilities will be returned in place upon equipment abandonment and installation. Peak Rate: The Project will not result in a change in impervious surface, pre-construction contours, or peak runoff rates. The regulation station development portion of the project is small and has a Built Upon Area (BUA)of 1.1%,well below the thresholds for a low-density development area. Additionally, the entire area of permanent grading will maximize water dispersion through vegetated slopes and shallow perimeter swales as well as pads being stabilized with porous 57 stone. Therefore, the impacts due to the regulation station should have little to no impact on existing flows in the area. Post Construction Water Quality: The Erosion and Sediment Control Plan has been designed to control pollution and protect water quality during all stages or phases of development. The project will not result in a change in the physical, chemical, biological, or radiological integrity of downstream waters. Sedimentology: The total disturbed area of the Project is approximately 52.8 5-1-8 5-1-:9 52.8 54.18 acres in NC. Site soils consist of urban land and sandy loams based on a review of USDA NRCS soils survey attached to this narrative. Applicable soils are mostly overlain by existing pavement and grass and vary from 2 percent to 25 percent slope.