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Home My WebLink AboutSW1240201_Stormwater Report_20240227 DESIGN REPORT STORMWATER MANAGEMENT PLAN Horsepasture River Wastewater Treatment Plant and Collection System Improvements Jackson County, North Carolina January 2024 Scott Burwell, PE NC Professional Engineer No. 039177 McGill Associates, P.A. 55 Broad Street Asheville, NC 28801 v SEAL o = Date: 039177 e License Number C-0459 2024.02.08 09:49:22-05'00' JANUARY 2024 STORMWATER MANAGEMENT PLAN HORSEPASTURE RIVER WASTEWATER TREATMENT PLANT AND COLLECTION SYSTEM IMPROVEMENTS JACKSON COUNTY, NORTH CAROLINA 1.1 PROJECT DESCRIPTION .................................................................................................3 1.2 SITE DESCRIPTION...........................................................................................................3 1.3 ADJACENT PROPERTY....................................................................................................3 1.4 SOILS .................................................................................................................................3 1.5 STORMWATER CONTROL MEASURES..........................................................................4 APPENDICES APPENDIX A SITE LOCATION MAP APPENDIX B DEED(S) APPENDIX C CALCULATIONS: WETPOND APPENDIX D CALCULATIONS: PIPES APPENDIX E CALCULATIONS: OUTLET PROTECTION APPENDIX F RAINFALL AND SOILS DATA APPENDIX G DRAINAGE AREA MAPS 1.1 PROJECT DESCRIPTION The project consists of the construction of a new wastewater treatment plant on the Horsepasture River and improvements of the collection system. The project is located on the Horsepasture River in Cashiers, Jackson County, North Carolina. Due to excess wastewater flows, the Tuckaseigee Water and Sewer Authority(TWSA) saw an immediate need for increased wastewater collection and treatment capacity in the Cashiers service area. The site will be accessed from across Horsepasture River on US Highway 64. In order to reach the site, a temporary stream crossing will be constructed to aid in the construction of a new permanent bridge. Once the bridge construction is complete, the temporary stream crossing will be removed and the stream will be restored to its natural condition. Financially Responsible Party: Tuckaseigee Water and Sewer Authority 1246 West Main Street Sylva, North Carolina 28779 Contact: Mr. Daniel Manring Executive Director (828) 586-5189 1.2 SITE DESCRIPTION The project site can be described as predominately high sloped wooded area. The average slope of the site south of the Horsepasture River is 17%. The average slope around the Horsepasture River is 2%. The grading operations will occur where proposed grades are shown on the plans. The site drains towards the Horsepasture River and runoff will collect into a proposed wetpond before discharging into the river. The site lies within a state-defined "Outstanding Water Resources Area"and drains into the Horsepasture River which is classified as a Class C, and Trout river. 1.3 ADJACENT PROPERTY The surrounding properties of the site are best described as predominately wooded with a few residential, single-family lots on the east side. The property across US 64 E is grass. 1.4 SOILS The extents of the project site contain soils with the following map unit names: Nikwasi fine sandy loam, 0 to 2 percent slopes, frequently flooded, group A/D (NkA), and Saunook gravelly loam, 15 to 30 percent slopes, group B (SaD). 1.5 STORMWATER CONTROL MEASURES According to Jackson County's ordinance for the Cashiers commercial area, the stormwater management plan must accommodate the stormwater run-off generated by a 25-year, 24-hour rain event within a designated Outstanding Water Resources Area and must treat the first inch of rainfall during any storm event. Therefore, the project's stormwater conveyance system and stormwater control measure have been designed to accommodate the 25-yr storm and treat a minimum of the 1-inch storm. A stormwater wetland was selected as the primary stormwater control measure for this project. The wetland is sized to detain the runoff from the 25-year design storm from all proposed built- upon areas associated with the project without utilizing the emergency spillway. The volume of the 1-inch storm is treated within the wetland. Most of the offsite stormwater runoff will bypassed around the project area and will not be treated. APPENDIX A SITE LOCATION MAP �• . ' r . L'�I •r rL PLAN ' ■ f w k. Or- __ ML 4F 0- Lu A A6 Nwq - Lu 11 z I &,, Y " I . %_ - - ?.Ink III L L jr,01p% . J) boO ''`� ire, - — -� ` 1 . . _ i ti 1 IF L +..� . -a �� o Q 16. 05-1 14 . 1 I r .161 z IN ui _ W O%w - 1 w + 1 W __e 101 4e w Vp ' ' ! IFS ■ ' ' `' < -1 + 1 w > � Lu - i r D L JJ ' ■ 'r " a'• .� REID REAL ESTATE 0- J ofL49 � 1 of - ■L t Q 1 � �. w Cn & '', PROPOSED DRIVEWAY ' '�`1 # - . Ilk < - � FL in- 9 .16 Lu pp� '. & - I PIP I _j Lu .11 .pie + 'Mp ' w ti w 11 i �1 - r co ' _ Q _ PROJECT SITE OWNER: � ' ■''- 1 �'' T r � ! TUCKASEIGEE WATER AND T 1 } - ` 'i12 J. SEWER AUTHORITY _ + %r r CD r"r' 1 PARCEL NO.: 7582-46-3638 o f wv ` r BK 2065/PG 337 • � '� - � - ■ rr ' " LUPTON LAKE O , JENNINGS BUILDERS SUPPLY JL ' r_% �- - •ti L AL •L 1 1 16 FL Jr JL Ir IN • L JL 1 + fi% • ti J _ + 1 ' L F CEDAR CREEK RACQUET CLUB � L �. + . 1 7 116i-IIV L • .� ,1 r �• - L SAPPHIRE VALLEY RESORT Of U .� ' - 1111114 . 1 7 J Ll - + 1� L - N - N W r 0.6 % 7. - or, - 1. ■ p E - ■ U % 3 _ LA 46- i 7 '-' 06' 'J .L - .1 C.) 7 L� �r Z o � �L IL i . co L O ■ r ' 0 200 0 100 200 400 SHEET gEFOR,6 HORSEPASTURE RIVER co WASTEWATER TREATMENT PLANT 55 Broad Street O V� , GRAPHIC SCALE DIVISION VALUE = 200 FEET VICINITY MAP ��` 1 AND COLLECTION SYSTEM IMPROVEMENTS wAsheville, NC 28801 �� ` o OFFICE MANAGER DESIGNER 828.252.0575 o� �9� �� TUCKASEIGEE WATER & SEWER AUTHORITY M. CATHEY N. SAWYER o NC Firm License # C-0459 F ��' Q �� QP� PROJECT MANAGER REVIEWER DATE PROJECT# FUNDING# m mcgillassociates.com GGING JACKSON COUNTY, NORTH CAROLINA K. SEAMAN JULY 2020 15.00391 USDA-RD NO. DATE BY DESCRIPTION _ J