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Home My WebLink AboutB09-0210 Arosa Duplex Mitigation Confirmation 030410www. vailffov. com March 4, 2010 1St Bank of Avon attention: Adina Dean Post Office Box 5270 Avon, Colorado 81620 RE: Mitigation of debris flow hazard at Lot 8, Block C, Vail Ridge, located at 2657 Arosa Drive, Vail, Colorado Dear. Ms. Dean, This letter is being provided as verification that certain measures have been taken to. address the Moderate Hazard Debris Flow on the above referenced lot. Prior to construction of the new duplex residence a study was performed by HP Geotech, dated August 6, 2009, identifying the extents and impacts of the hazard designation on the lot. In response to this report a method of mitigating this hazard was designed and installed. In a letter written and signed by David A. Young, a Colorado Registered Professional Engineer, with HP Geotech dated November 16, 2009, it was identified that the mitigation solution was constructed per the engineering requirements. These documents are attached for your reference. If you have any further questions please feel free to contact me by email at wcampbellCa7vailgov.com or by phone at 970-479-2148. Sincerely, - Warren Campbell, AICP Chief of Planning Town of Vail xc: File Attachment *RECYCLED PAPER k 1111 HEPWORTH-PAWLAK GEOTECHNICAL August 6, 2009 J.L: Viele Construction, Inc. Attn: Brent Arnold 1,000 South Frontage Road West, Suite 202 Vail, Colorado `81.657 Subject: Conceptual Debris Flood Mitigation Concepts; Lot 8,, ;Block C; Vail.Ridge, 2657 Arosa Drive, Vial, Colorado Gentlemen: As discussed in our telephone call with you and Mark I iinabf Peal;. !,and. Consultants on. August 4; 2009; we are providing conceptual debris flow mitigation concepts for the. proposed. duplex at the. subject site. We previously conducted a. debris flow and risk, assessment of the property:and;presented:.aur findings ui a report dated July 24, 2009,. Job No. l'09 226&1 Building the project as shown on the conceptual site plan and providing: a .high level of protection against debris flood impact will not be practical. We:discussed moving the' building to the east and reconfiguring the east unit to provide space for ad, wall between the building and the. existing flow channel. Filling .in the. drainage for the driveway will constrict flows. A box culvert can be provided below the driveway but the drainage flows into an undersized culvert ; below the site that will backup in a design flow event. A lame debris flood event could overflow the.ex sting 61iannel and flow onto Arosa Drive: llen;oi?rcl1 l'rttla :ti p[e tl iic;il, Inc, 5 0r gn4R dlye ~,lt tm i< <i ` p b(pj C ,u]Ora)Lhil 8.1601 I'honu: 9.70-94549~8 rx:970.948 8454 e t^.iL•. hi-, rv hl,j F)ge(,i edIxcir t Job No. 109 226A +Conceptual Mitigation Concept: Provided the duplex-owner accepts: the potential.for fiont at least 2 feet:above the:building. rovide.a"low ride of impa lie, potential. Wlien the 1, we should evaluate the: reduction of the risk to the site for acceptance by the duplex owner. .If, you have any, questions or need further.assistance. please let us know. Sincerely,. HEPWORTH - PAWL AI rBz i JNC.: h . Steven L. Pawlak; P:.. " Rev. by: DAY SLPlksw cc: J.L. Viele Construction Peak. Land Consultants Scott Ashburn, (scott cr v eleconstiuetion:coin) Mark Luna, PE (luna@peakland.not) i-ker 0:7-841-71 19 - ('01orado. Springs 719,663-5,562 o Silverrho me 970-468.-1989 1n H.epw . rth hitit t tl` Oeotc ?inic_,;I, Inc. 5020 County Rc ad 154 Glellt5OMI sprig g"i t olo ttuC) 81.601 Yam cg 't `c'" 1 Phooe:970f945.1988 PIET ORTH=PA4VLAK GE OTECHNICAL Ft x:970-945-841 entail: 1z1,!ect`•t?i~r erx+:+>1..c :m November 16,, 2009 J.L. Viele Construction, inc. Attn: Scott Ashburn 100080' th Frontage Road West; Suite 202. Vail, Colorado 8;1657 Job No. 109 226A Subject: Observation. of Boulder Deflection Merin Construction for Debris Flood Mitigation;. Proposed Duplex, L.ot. 8, Block C. Vail Ridge,, 2657 Arosa Drive, Vail, Colorado Dear. Scott: As requested; we observed construction of the. debris flow mitigation boulder deflection berhi at the subject site on Noveixiber:3,.:44 and 12, 2009. The purpose of our observations was'to evaluate. compliance with our previous recormnendations. The;boulder berm deflection wall is part of the debris flow mitigation for the site development. :Recommendations for the boulder deflection wall were provided in our debris flow mitigation report for the site dated August 3 2009;, Job No_ 109 226-. Can N:oveinber, 3,. constructions of the boulder berrxi was just underway and we met with the contractors to discuss the proposed; construcdoh.. At this thile, the 30 in ch diameter culvert below the proposed drivewgy.had been. installed and the building foundation. back-fill was. essentially complete. On November 4, construction of the berm was proceeding orii south to i ortl . At the time of our NoWiribez 12 site visit; the berm was essentially completed.,. The deflection. bernlAs located just west ofthe. duplex. currently udder constmction.afthe site The. berm,is from about 4K to 6 feet tall with the louver portion, of-the berm. anchored into the ;h §ide soutliw. 68t ofthe duplex. The beiiii was constructed`witli about 2 to:5..:feet diameter:.suban'! ar to angular boulders embedded about 1 foot in fhd natural ground surface: Th'reconlinended 2 feet of eiribedu ent was obtained bv:aa additional 1 foot of fill along the front side The westeii' ,boulder side of the berm facing the. drainage channel was battered back at about :Y2 (horizontal) to f(vertical). 'Filter :fabric was,placed on the. eastern, down, drainage: side of the boulders to. separate the boulders:.from the on- site soil backfill,. The baclefill slope;ofthe berm*was ,front about l to 1!/2 (h) to 1 (v) 00w11 to a shallow drainage swale near the duplex: The boulder berm has. been constructed in. general accordance with our previous recommendations. The steep backfill slope will t6nd:to erode.and slump aril should be either flattened to the design drawing grade of l3/ (h) to 1(V) or retained at the toe such as with another boulder wall to provide the flatter slope. grade prior to .revegetaY on. Regular m1aintenance to the deflection berm, especially after a debris flood event, should be lPr il.(.er 303-841-71:19 G C olorado Springs 719.633-5562 0 Silverthorne 9704584989 J.L. Viele Construction, Inc. November 16, 2009 Page 2. expected. Other applicable recon-unendations and precautions provided in our previous reports should also be observed. If you have any questions or need further: assistance, please let us know. Sincerely, INC. David A. Young, P.E. Rev. by SLP DAY/ksw cc: Peak Land Consultants - Attn: Mark Luna, PE (luna@peaklaind.net) Job No. 109`226A ~~te~