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HomeMy WebLinkAboutFile Documents.617 W Bleeker St.0052-2022-BCHO (5) Crystal River Civil LLC 970.510.5312 Page 1 of 2 617 West Bleeker Driveway Slope Variance Request To: City of Aspen Engineering Department 427 Rio Grande Place Aspen, CO 81611 From: Vince Tomczak, P.E. Crystal River Civil LLC (970) 510-5312 vince@crystalrivercivil.com Date: June 21, 2022 Re: 617 West Bleeker Driveway Maximum Slope Variance Request A variance for the maximum driveway centerline slope is being requested for the access onto 617 West Bleeker Street. The development is currently permitted and the single-family residence is nearing completion. Due to micropile shoring walls being surveyed in the incorrect location, it has been identified that the structure shifted approximately six feet to the south from the previously approved design. The shift had not been detected until the as-built survey was completed. The footprint of the permitted structure remained the same, and the building is still located outside of setback requirements. However, adjustments had to be made to account for the changes. These changes are accounted for in the Change Order #1 set dated June 21, 2022. To maintain access to the constructed garage, CRC cannot design a driveway that meets the City of Aspen Engineering Standards. Code Reference: City Of Aspen: Engineering Standards 4.1.4 (Page 29) Access Design Specifications (Non-emergency) - Maximum allowable slope of a driveway shall not exceed 12%. The centerline profile of the driveway is required to not exceed the 12% allowance as stated in the engineering standards. To install a driveway that safely enters the garage from the alley, it is requested that the driveway slope can be increased to 13.5%. Maintaining a 12% slope is possible, however it will not allow for the adequate transitions. Slope transitions from the alley and into the garage are prioritized to ensure typical passenger vehicles can ingress and egress the residence from the garage. In the proposed design, AASHTO K-values were utilized to allow for safe transitions between slopes for parabolic vertical curves on centerline profiles. These curves make the transitions smooth, rather than abrupt grade breaks. Two vertical curves are proposed within the centerline profile, one at the alley and one at the garage entrance, each twelve feet long. A K-value of 1 to 1.5 is used for the design of the driveway, which is deemed adequate for the low speeds and the site constraints. A 5.9-foot long tangent section slope at 13.5% is located between the curves to drop to the garage finished floor elevation. 07/11/2022 Reviewed by Engineering 01/18/2023 8:19:48 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 The concrete driveway is to be snowmelted, and a trench drain is located at the low point of the driveway and garage entrance interface to capture runoff. Using AutoCAD Civil 3D analysis tools, there is only an eleven-foot section of the driveway that exceeds 12% slopes - the tangent section of the profile and small sections of the vertical curves. Image 1: Centerline Profile of the Snowmelted Concrete Driveway In order to accommodate the engineering standards maximum slope requirement, the project would have to install a driveway with no transitions, which would eliminate general use of the garage or the driveway. Alternately, the house would have to be demolished and reconstructed in the previously permitted location to allow for adequate space for the access. Please refer to the civil drawings for additional information and details associated with the driveway at 617 West Bleeker. If there are any questions regarding this variance request, please contact me via email or phone. Sincerely, Vince Tomczak, P.E. Crystal River Civil LLC 07/11/2022 Reviewed by Engineering 01/18/2023 8:19:56 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.