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HomeMy WebLinkAboutFile Documents.934 S Mill St.0281.2018.ARBK1 Drainage Report For Minor Design 934South Mill Street Aspen, CO 81611 Change Order 1: November 1st, 2018 Prepared by: John Galambos/Anna Reynoso Galambos Architects Inc. 314 AABC, Suite D 11/27/2018 Reviewed by Engineering 12/18/2018 8:45:10 AM "It should be known that this review shall not relieve the applicant of their responsibility to comply with the requirements of the City of Aspen. The review and approval by the City is offered only to assist the applicant's understanding of the applicable Engineering requirements." The issuance of a permit based on construction documents and other data shall not prevent the City of Aspen from requiring the correction of errors in the construction documents and other data. 2 Aspen, CO 81611 Table of Contents: 1. General 1.1. Existing Site 1.2. Proposed Project 1.3. Drainage Issues 1.4. Offsite Drainage & Constraints 1.5. Downstream storm water conveyance system. 11/27/2018 3 1. General 1.1 Existing Site The residence under evaluation is located at 934 South Mill Street in Aspen, Colorado. The property is a .284 acre parcel. It is bounded by residence on the South/East and West side with a shared Access Easement on the South/East side for a shared driveway to Top of Mill Street. To the South, the property line is up against Aspen Mountain. The existing structure includes a 9,113.4 square foot residence with a finished garage. The residence is built below Aspen Mountain on a moderately steep site with an existing concrete deflection wall and an existing 1.5’ stone mudflow wall. Most of the site drainage pattern is using the slope of the existing mountain into water quality filter vault. A large terrace is located North of the retaining wall and South of the existing house (which is partially in the setback). An ADU is a separate building located South of the main residence next to the large main house terrace. Trees and shrubs are along the border of the property between the neighbors on the South/East and West side. The existing concrete driveway is located on the North side of the property in the access easement shared with the neighbors. Most of the site drainage plan is utilizing the existing site drainage that was approved in 2010 and per the Aspen Mountain PUD. The slope of the existing mountain gets directed around the mountain home per the Aspen Mountain PUD. W ith swales to drain basins and the storm drain system as approved. The house utilizes a previously approved water quality filter vault located on the west side of the driveway; see original Top of Mill, Lot 5, Stormwater Drainage Piping and Utilities Plan dated June 29th, 2010. 1.2 Proposed Project The result of Change Order 1 from original permit is due to the disturbance area being more than 200 sf but less than 100 sf. This project is classified as a ‘Minor’ project includes those that add or disturb 200-1000 square feet or soil or impervious area. There are a few areas that will be changing on this site that have minor impact. All details are located in the architectural drawings. Listed below: 1. Addition a. The owner is removing part of the existing patio on the South side of the main house to create a larger breakfast area. (Part of original submittal) 2. Removal of house a. The owner is removing part of the house on the South/West side. A stone ledge will replace this area. The water will drain to the existing slot drains and green space. (Part of original submittal) 3. Breakfast Stoop a. The owner is adding a stoop of the existing patio at the new breakfast area on the South side of the main house. There is an existing slot drain 11/27/2018 4 South of this stoop that the water will drain to. The existing patio currently has snowmelt which will be transferred to the proposed stoop. (Part of Change order 1) 4. Living Room Stoop a. The owner is adding a stoop over the existing patio at the living room on the South side of the main house. There is an existing slot drain South of this stoop that the water will drain to. The existing patio currently has snowmelt which will be transferred to the proposed stoop. (Part of Change order 1) 5. BBQ a. The owner is adding a built in BBQ on the South side of the patio, covered by the roof overhang. (Part of original submittal) 1.3 Drainage Issues The exterior alterations will be a similar drainage pattern as existing. No drainage issues should be caused with this alteration. 1.4 Drainage Basin and Drainage alterations We are not are not altering the flow of the existing swales. The snowmelt currently exists on the pack patio and will be altered to accommodate the stoops. The snowmelt will not drain to the right of way. 1.5 Downstream storm water conveyance system. There are not changes in the storm water conveyance system. Minor (green) 11/27/2018