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HomeMy WebLinkAboutFile Documents.605 S Alps Rd.0007-2020-BCHO (4) To: Jack Danneberg Aspen Engineering Jack.Danneberg@cityofaspen.com 970-429-2750 From: Robert G. Garza Roaring Fork Engineering 592 Hwy 133 Carbondale, CO 81623 robertg@rfeng.biz (970) 340-4030 ext. 710 Richard Goulding Roaring Fork Engineering 592 Hwy 133 Carbondale, CO 81623 richardg@rfeng.biz (970) 948-7474 605 and 675 S. Alps Road Drainage Memo Jack, The project is located at 605 and 675 South Alps. It is a landscaping effort around the residence with minor grading at the southside of the residence. The project site is located at the base of Aspen Mountain at the end of South Alps Road in Aspen, Colorado. The purpose of the project is to improve the landscaping of the home and add screening for privacy. The landscape work and minor grading at 605 and 675 South Alps Road does not adversely affect the drainage patterns onsite or offsite. This report addresses the changes from existing conditions to design improvements of the landscaping and grading. The residence was completed in 2017 and all runoff meets the requirements of the URMP. Prior to improvements: Under current conditions, 675 South Alps is a single-family residence on a 1.37-acre property located near the base of Aspen Mountain. The property is surrounded by a large slope on the southwest side of the home with an average of 2:1 slope coming off the mountain. 605 South Alps is an unoccupied 1.39- acre just east of the home, this lot is used for open space recreation and landscaping. properties are surrounded by extensive landscaping, including sodded lawns, shrubs, and trees. Adjacent to the northeast of the properties there is South Alps Road, a dead end that is used for access by a half-dozen homes. There are stone steps on the southside, adjacent to the residence. The residence does see some runoff from Aspen Mountain, however, a storm collection system was designed previously to convey runoff around the home during large storm events and seasonal runoff. 01/29/2020 605 and 675 S. Alps Drainage Memo January 7, 2020 Page 2 of 2 Landscape and Grading Improvements: The proposed work to be done is improved landscaping to the northeast and south of the existing residence and minor grading to the south of the residence. The owner is going to replace stone steps adjacent and south of the home with sodded steps. Improved landscaping to the north and east of the residence will be implemented. See the landscape architect plans for a planting plan. There are no design improvements planned that would increase the impervious area on site. Erosion Control: The property sits at the base of Aspen Mountain with average slopes of 2:1 and therefore will require extensive erosion BMP’s to mitigate a significant storm event. During previous construction of the property, a swale was constructed at the toe of slope just upstream of the home to convey flow away from the footprint of the home. The contractor will implement a stabilized construction entrance and use the access easement that lies on the northeast side of the property, adjacent to South Alps Road. Sod will be placed over topsoil immediately after the new grading, so an erosion control blanket will not be required. During grading, a silt fence will be trenched and placed downstream of the grading, as well as staggered soil control logs on the slope of the newly graded area. The planting beds will have soil control logs staggered along the slope until finished planting is achieved. Soil control logs will be installed and maintained at the downstream perimeter of 605 and 675 South Alps to prevent any disturbed soil from leaving site during a storm event. See sheet C3 of the civil drawings for the overall stormwater management plan. If you have any questions, feel free to contact us at Roaring Fork Engineering. Sincerely, Richard Goulding 01/29/2020