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HomeMy WebLinkAboutFile Documents.1050 Matchless Dr.0113-2020-BRES (19) P.O. Box 3901 YARNELL CONSULTING & 229 Midland Ave. Eagle, Colorado 81631 Basalt, Colorado 81621 CIVIL DESIGN, LLC (970) 323-7008 • 3/23/2021 Carly McGowan City of Aspen Engineering Department 201 N. Mill Street,Suite 101 Aspen, Colorado 81611 carly.mcgowan@services.cityofaspen.com Subject: 1000 Matchless Dr_Engineering Comments 1 Comment Responses Carly: Thank you for your thorough review of our project. Please find your comments and the associated responses listed below for the above-referenced project. 1. Sheet Cl "Cover Sheet". In Drainage Report, address the emergency overflow route for the BMP. YCCD Response:This has been added to Section 6.2 of the Drainage Report. 2. Sheet C1 "Cover Sheet". Page 43 of the Drainage Report shows that exploratory boring resulted in drill rig refusal at 8'below grade. If there are large boulders that prevented drilling, then the BMP will not infiltrate. Please address the plan if this is the case. YCCD Response: Drill rig refusal is very common in and around the city of Aspen. Much of the soils contain cobbles.While they are large enough to stop a drill rig,they are typically not large enough to keep an-200 square foot system from infiltrating. In the highly unlikely event this is discovered once the excavation is opened,an alternative design will be generated.There are options such as relocating the detention system or removing the rock that could be viable.This is yet to be an issue on any project for us to-date-both in the city and beyond. 3. Sheet C1 "Cover Sheet". In Drainage Report, address water quality capture volume and show that it is incorporated in the detention volume. YCCD Response: This is already stated in Section 4.9 of the report.The volume calculation is in Appendix C. 4. Sheet C6.1 "Detailed Utility Plan". The existing gas main needs to be potholed and the exact depth determined.Any necessary alterations to the gas main need to be determined and shown on the plan set prior to permit issuance. YCCD Response:We have altered the drawings to show relocating the natural gas service as required based upon the proposed storm sewer infrastructure. 5. Sheet C7.1 "Details': City standards require a maximum slope of 3:1. Please revise. YCCD Response: The detail has been revised. RECEIVED 1000 Matchless Dr_Engineering Comments 1 Pagedg5612021 ASPEN BUILDING DEPARTMENT P.O. Box 3901 YARNELL CONSULTING & 229 Midland Ave. Eagle, Colorado 81631 Basalt, Colorado 81621 CIVIL DESIGN, LLC (970) 323-7008 • 3/23/2021 6. Sheet C3 "Site Plan". Limits of disturbance are shown to cross property boundary. This is not allowed unless project has received a letter from neighboring property stating acceptance of limits of disturbance. Does project team have permission to remove retaining wall on neighboring property?Verify with signed agreement from neighboring property. YCCD Response:Yes,this permission has been obtained.The approval letter is being included in the resubmittal package. 7. Sheet C3 "Site Plan".A swale is required along the length of the property to handle drainage from the roadway. The swale should tie into the existing swale along 980 Gibson.Show how drainage will be accommodated given current grading and tree location. The disturbance area requires a major review which requires public improvements along the entire length of the property. YCCD Response:We have marginally reduced the disturbance area to permit this project to be reviewed as "minor";therefore,omit the need for public improvements along the entire length of the property. 8. Sheet C3 "Site Plan". This property is not in a sidewalk deferred zone.At this time, a sidewalk is not required but it may be in the future. Please sign and notarize the sidewalk agreement form. YCCD Response: The executed document is being included with the resubmittal. BMA Response: This document is under review and will be signed, notarized, and uploaded prior to permit release. 9. Sheet C3 "Site Plan': The storm water system is shared infrastructure and therefore must be designated as a greater common element on the condo plat. Please verify that the existing plat covers the shared infrastructure or that a new condo plat will be recorded. YCCD Response:A new plat will be required in order to relocate the platted (assigned) parking stalls.The shared infrastructure can be added to the new plat. 10. Sheet C5.0 "Overall Grading Plan': What is the proposed depth for the BMP chamber system. Show bury depth on plans. YCCD Response: Refer to the"Below-Grade Detention System Notes"on Sheet C6.1.The bottom of the excavation is 7943.85 while the top of gravel (bottom of chambers) is at 7944.60. 11. Sheet C5.0 "Overall Grading Plan': Because this BMP is being used for detention, the drainage report needs to show that freezing isn't an issue and water will infiltrate should there be a significant rain event in the winter months. The bottom of the chamber where water will infiltrate must be at least 7'below grade because of frost depth. YCCD Response:To be clear,frost depth in the city of Aspen is four feet-not seven.That is why building foundations only have to go down to four feet. But in this case,the bottom of the chambers is far deeper (to be below the basement slab of the existing residences).While finished grade is -7953,the bottom of the chambers is at 7944.60. 12. Sheet C5.0 "Overall Grading Plan': Verify entire parking lot within the property line drains to the BMP.It appears this section (west of unit 1 garage)will drain to the ROW. RECEIVED 1000 Matchless Dr_Engineering Comments 1 Pagedg5612021 ASPEN BUILDING DEPARTMENT P.O. Box 3901 YARNELL CONSULTING & 229 Midland Ave. Eagle, Colorado 81631 Basalt, Colorado 81621 CIVIL DESIGN, LLC (970) 323-7008 • 3/23/2021 YCCD Response:A trench drain has been added along the ROW limit to intercept the nominal quantity of surface runoff not previously slated to be captured. Sincerely, \V ,c Justin J.Yarnell, PE Colorado PE Number 47241 RECEIVED 1000 Matchless Dr_Engineering Comments 1 Pagedg5 612021 ASPEN BUILDING DEPARTMENT