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HomeMy WebLinkAboutFile Documents.905 Chatfield Rd.0111.2018 (63).ARBK An Employee-Owned Company 1517 Blake Avenue, Suite 101 Glenwood Springs, CO 81601 Telephone (970) 945-8676 Fax (970) 945-2555 Land Surveying Civil Engineering February 09, 2021 Hailey Guglielmo, P.E. Project Manager City of Aspen Engineering Department 201 N. Mill Street, Ste 203 Aspen, CO 81611 RE: Grading and Drainage Certificate Conditions for TCO Permit No. 0111.2018.ARBK, 905 Chatfield Road HCE Project No. 2171653.00 Dear Hailey: High Country Engineering, Inc. has been requested by G.F. Woods Construction to provide the as-built survey for the Grading and Drainage Certificate approval to be issued a Certificate of Occupancy (CO) for the project at 905 Chatfield Road. However, due to the site winter conditions, the grading and drainage of the site cannot be fully analyzed to assure the compliance of approved plans and the complete functionality of the final grading and drainage. It is our understanding that a Temporary Certificate of Occupancy (TCO) may be issued until the spring weather allows a more accurate survey and site grading and drainage to be fully verified. The contractor and owner have agreed to satisfy the conditions of this letter and the attached markup of the preliminary as-built survey, to obtain an approved Grading and Drainage Certificate prior to the TCO expiration date. The following items must be completed, verified and approved prior to the June 25, 2021:  Grade inlet rim elevations to provide adequate drainage with the final landscape grading.  All swales must drain as designed and provide adequate capacity for 100-year storm event.  Positive drainage away from building foundation with greater than or equal to the minimum slopes specified in the geotechnical report or as shown on plans. Hailey Guglielmo February 9, 2021 Page 2  The bioretention pond grow media mix must verified to be at least 6 inches below the weir crest with final landscaping.  Verify outlet pipe elevations and level spreader functionality with final landscaping.  Verify all drainage paths drain to the WQCV vault or bioretention pond with final landscaping installed.  Verify bioretention pond overflows weir into swale and rip-rap once final landscaping has been installed.  Final landscape grading shall be surveyed for slopes and spot grading.  Section views of drainage infrastructure with storm capacities, gravel depths, grow media depths, and overflow paths with final landscaping. Storm pipes were installed by the general contractor with higher elevations, and in some instances lower slopes, than proposed. We have reviewed the installed drainage infrastructure and we believe there is no impact due to the change in elevations. The original design had conservatively sized drainage infrastructure to capture and convey the entire proposed drainage basins for the 100-year design event. We ran hydraulic calculations to reflect as-built conditions, and the drainage infrastructure will convey the 100-year design event as intended. A preliminary as-built with comments to indicate the tasks that need to be completed in the spring is attached. HCE has provided this document to address the City of Aspen engineering grading and drainage certification in the spring of 2021. Gathering accurate survey data for grades and drainage infrastructure during the months of heavy snowfall can provide information that will not reflect the final as-built conditions. The site will need to receive final landscaping for CO in the spring, so at this time the as-built survey will be updated and stamped by a professional land surveyor and engineer for City of Aspen approval. Please let me know if you have questions or comments. Feel free to contact me if you require any additional information. Sincerely, Roger D. Neal, P.E. Principal IVBCOCOBYNO.DATEPROJECT NO.REVISIONHIGH COUNTRY ENGINEERING, INC. PHONE (970) 945-8676 - FAX (970) 945-2555 www.hceng.com drawn by: checked by: date: file: 1517 BLAKE AVENUE, STE 101, GLENWOOD SPRINGS, CO 81601 COLORADO 811CALL BEFOREYOU DIGUtility NotificationCenter of Colorado2171653.001G.F. WOODS CONSTRUCTION 905 CHATFIELD ROAD CITY OF ASPEN, COLORADO PRELIMINARY GRADING & DRAINAGE AS-BUILT SITE PLAN BDB RDN 02/09/21 ASBUILT.DWG 905 CHATFIELD ROAD, ASPEN, COLORADOMORE PARTICULARLY DESCRIBED AS LOT 4, WEST ASPEN SUBDIVISION, FILING No. 3SECTION 2, TOWNSHIP 10 SOUTH, RANGE 85 WEST OF THE 6TH P.M.COUNTY OF PITKIN, STATE OF COLORADOPRELIMINARY GRADING & DRAINAGE AS-BUILTPROPERTY DESCRIPTIONNOTESVICINITY MAPSCALE 1 500 LEGENDAS-BUILT SURVEY CERTIFICATION STATEMENTGRADING & DRAINAGE CERTIFICATECOReviewed by Engineering02/17/2021 11:18:07 AM"It should be known that this review shall notrelieve the applicant of their responsibility tocomply with the requirements of the City ofAspen. The review and approval by the City isoffered only to assist the applicant'sunderstanding of the applicable Engineeringrequirements." The issuance of a permit basedon construction documents and other data shallnot prevent the City of Aspen from requiring thecorrection of errors in the constructiondocuments and other data.