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HomeMy WebLinkAboutadditional.exhibitsADDITIONAL EXHIBITS SUBMITTED AT THE DECEMBER 21, 2005 PITKIN COUNTY BOARD OF COUNTY COMMISSIONERS REGULAR MEETING EXHIBIT AGENDA ITEM EXHIBIT DATE NO. A Appeal by Terry Taylor of Letter to from November 8, 1985 Earthmoving Permit Issued to Nicholas Lampiris, Tom Lewis PhD, to Dean Gordon, Schmuesser & Associates B Appeal by Terry Taylor of Letter from NicholasApril 6, 1988 Earthmoving Permit Issued to Lampiris, PhD, to (Written in) Tom Lewis Wayne Etrhridge C Appeal by Terry Taylor of Comments by Peter November 8, 2004 Earthmoving Permit Issued to Schaerer to Appeal Tom Lewis Reply by Matthew Ferbuson, dated November 5, 2004 RE: Little Cloud Subdivision, Aspen - Taylor Residence November ~len~ood ~prings~ DO. D!~C)i Shadow Mountain -- East hays complsted my geologic ins. estigation, as required by ~on esi bl ey. Lode Mining - F. BloCk 47, AdditionallY (s~e a~compmnyin~ map), the ='-= ~ and' Third Street. This is ~ithin thm As~mn 7 !/2 minute quadr~ngi~.~ Pitkin Countv~ The tooog6~hY o~ this lower portion of the subject property con.~ists of the mtmep~ northemstmrn slmping hillside mt the base o~ Shado'~ Mountain where it merges ,xith ism artificial berm ~hich is the Colorado' & ~idland~ right-of-waY. Tankard the sou.,east there is'-~ ·longs linear deoressimn bmtw~mn the base of 'the mo~ntmin ~nd the mid railromd bed. Therm is a prominent bmnch mt the base .of thm Copperopolis claim, approximately 70 f~t above the bmsm of ~hm depression and west ~ it. Most o~ the hilisid~ is covered with conifers up to ten to twelv~ inches in diameter. ~here are large li'mestonm ~nd dol°mite 'blocks scattered i!.ong the hillside and its base with a we!l developed foot path system all .along the hi!!sidm t~'~ard the bms~ ~f the ~here arm several mine dumpS~ indicmting min~ workings, in thi~ area. The geology of the site consists ~ colluviml and t'aius materi~l ~hich has b~mn derived over the centuries ~rom the cmrbonate and sandStOne outcrops mbove. This material rabies +~ proposed No outcrops wer~ ~isLb~m ~ithin _~,e armm ' development. ~m =,andstonms and carbonate units on the - mul ted Leadvil ! e mountainside above th~ _/tm arm mostI]~ the-~ Limestone, MmnitOu Dolomite, and Smwmtch ~uartzitm the site, it is dif4icult to ascertain What uni~ or units DD000488 underlie the proposed development site, but it is probably either the Belden Shale or one of the prsvious!y mentioned +rom ~75 indicate that no bedrock was encountered to at dipping, even overturned, west limb of a north-so,th trending syncline on Aspen Mountain. The Castle Creek fault zone pas~es just west of the sub,eot area. it is my ~ndersta~ding that several dwellings are to be proposed ~n these properties, i will delineate portions of the property which have minimal geologic hazards or where the hazards can be mitigated. The geologic concerns on this 1. Steep and potentially unstabie slopes. 2. Rockfal! zones. 3. Snow slides and avaian~hes. The best area for development is'the roughly cir~u!ar bench previously alluded to at the base of the Copps~opolis claim. ~ecause of the'dense tree ~over on the hillside above the bench, the distance from the rockfall source above, and the general configuration of the hillside, i do not believe that falling rocks could reach this eit~e except in the most ' unusual circumstances, such as a very strong earthquake or blasting of the rock ledges above during some potential future construction. As long as the hillside behind this bench is not cut, these slopes should remain stable. Minor snow sliding, but not avalanching, is possible. There is also 'a'potential building envelope directly below this bench at the base of the hillside appro×imately as shown. ~is is generally a suitable site because of the sheltering effect.of the. topography above, which should not allow ~ocks or enow'slides 'to/reach the site. If the base of this slope must be cut for foundation construction, it should be done with care and the resulting foundation wall designed to act as a retaining wail, replacing the supporting material which will have been removed. Drainage within this depression must be made positive so that ponding does not occur during spring runoff or thunderstorm activity, thereby DDO004-89 DD0~_~492 ~a'yn e Ethnidge P.D. Bo;: ._-'-,S~.~, Aspen CO Bl~i2 Nicholas Lampids, Ph.D. EXHIBIT _~hrl bge: ! have completed my geologic investigation for purposes of House Bill 1041 of four sites ~ithin the above referenced project. The developable ares lies south cf the Colorado Midland right-of-way on the south side of the Town of .As~en between First and Third Street. This is within the Aspen !/2 minute quadrangle, Pitkin County, Cc!oradm. The topography of the lower portion of the property consists of the steep, northeastern-sloping hillside at the base of Shadow Mountain ~here it merges with the artificial berm which is the Colorado & Midland right-of-~ay. Toward the southeast there i~ a long, linear depression between the base of the mountain and the old railroad bed. There is a prominent bench at the base of the Copperopolis claim approximately 70 feet above the base of the ~eprsssion and west of it. Most of the hillside is covered with conifers up to 10 to 12 inches in diameter. There are a number of limestone and dolomite blocks scattered along t~e hillside and its base with a well developed foot path system all along the hillside toward the base o~ the cliffs above. There are several mine dumps, indicating previous mine workings, in this area. The geology of the site consists of colluvial and talus material which has been derived over the centuries from the carbonate and sandstone outcrops above. This material ranges from c~ays, silts, and sands to angular rocks and boulders. No outcrops ~ere visible within the area proposed for development. The sandstone and carbonate units on the mountainside above the site are mostly the faulted Leadville Limestone, ~anitou Dolomite, and Sawatch Quartzite of F'aleozoic age. Because of the complexity of the geology of the site, it is difficult to ascertain what unit or units underlie the proposed development site, but is probably the Belden Shale or one of the previously mentioned units. .T~=+ on Aspen ~untain. The Castle Cr~k ~aul~ zone passes just Although each cf the 4our sit~s will be discussed separate!y, 1. S~e~p an~ potentially unstaO!e slopes Building site ~4 is mt the wmst end cf ~h~ ~mve!o~mmnt et the west ed~m cf a natural bench which should provide a suitable site ~or develOpmmnt. Very little hillside cottin~ will necessary, e.nd rock4all a.n~ snow sli~e hazard i$ a~ a minimum c.oni~rs ~n the hillside a~ve the site. Nevertheless, ~~~~ve finished ~n~c~smry ms weli ~it= =~ecif~c :oils enoineer-no ~'~ - - positive ~rainage around the site. Buildin: site ~5 is a~ the narrower southeast end of this b=n~h. 'Because of this, more of a bil'lside cut ~ill be necessarY. Even thouoh the hiilsid~ is somewhat gentler here th:n =lsewr, er~. it is very imporsmnt ~hat the rear wall act as a retaininq wail to replace the material excavated. The mame conditions and mitioative recommendations for the previously described si%~ will also pertain here. ~n addition, I believe that it is important to conduct a factor o4 safety analysis on the hillside where the tom will be ~O~/~ , Building site ~2 is on a bench formed Dy old tailin~ workings out ~ th~ Alabama Tunnel. The tailings have been in plac~ 4cc a long time and should De 4airly stable~ but sit~ specifi~ soil5 8mgineerin~ ~iil be necessary. The rear o~ the hommsite should be landscaped so as to direct any more open to s~l enow slides and minor rock~m!l than ~h~refore. i rec¢~d that a small berm~trench preViOUs two: _ - . ' protect aqains% these two hazards. The berm portion of this 4mature ~hould be piled and compacted to at lea~ 85% Proctor pitbn Co Dbt Cpu~ O~ CF 208 Exhibit F ~. es__,,~al~y==-~ flat site =~-' the bass Building site in pitt by the railroad bed. s~.~.ll snow slides mhd ro~k fall. The recommendations for the oreviousiy desoribed sitm will all ap~ly here with the aO~itional recommendation that the depression be we!l-drained so that pdnding ~i!l not adversely affect the site. it is my understanding that municipal wate~ ~nd waste dis~osat systems are available. Access to site easy because of its iow level and proximity to the streets of Aspen., but sites ~2 through ~4 will need to be engineered alono a fairly stee~, but relatively stadia, hillside. 7her~ are no ~eotogic :onditions which will act to make this design any more difficult than elsewhere in the Count?' where hillside roads must be built. An additional recommendation is that the finished homes be d~signsd with adequate ventilation et lower ievels to minimize the a:cumulation of emitted in the area. The~e are faults in this area, but they al~n~ them in recent years, t recommend that the Uniform Building co~e ~e ~ollowed as it pertains to Seismic Zone II. I Jelieve that these sires can ali be develope~ as ~ndica~ed if the precsdin~ recommendations are fol!m~eO. In addition, ! believe that it is important that I be present during the staking of each building site and tbs euggesteo lanbscaping features, bs~auss they are so important to the droject. If there are further questions, please do not hesitate to ~ontact me, Sincere! y, ..' / ~ / Nicholas Lampiris Consulting Geologist ROA 1116 Pitkin Co Dist Court 94 CF 208 Exhibit F PETER SCHA_ERER November 8, 2004 Little Cloud SnbdbSsion, Aspen - Taylor Residence Comments to Appeal Reply by Matthew Forenoon, dated November 5, 2004 Following are my comraents about avalanche safety concerns that Fergu~on has mi~ed in his re-ply to the submis~on ofKraba~ber & Sand~rs dated October 22, 2004. RockIall Fence I am confident that American en~neers and steel mxpptJer~ are able to design and build a fence that would withstand the estimated avalanche forces and would not be damaged and be tom away. The fence may not be a standard rockfaI1 fence from the supply of GcoBragg, but the net, connections, posts and anchors could be designed ~pecifical]y for this location. Some avalanche snow would pass through the net, a part would.stop at the net and, depenaing on the speed and size of the avalanche, snow would flow over the top of the net and fail to the road below. I gather from the corrempondenoe of Lex~Ss, Ferguson, Mears that a rockfall fence would be located above the road. I am surprised to ]earn that the rockfall defeme ~n'ucture is allowed above the road, whereas avalanche con~o] works are taboo there. The bench above the road would also be the best place for catching avalanches. Avalanche lqazard at the Taylor BuildMg The building is .in the red zone according to zoning guidelines of the USA and other countries (see The Avalanche Handbook by McClung and Schaerer 1993; page 204) and in Canada ( Craidelines for Snow Avalanche Risk Determination and Mapping in Canada; Canadian Avalanche Association, 2002). The building is in the red zone because, a) avalanches may reach it more frequently than once in 30 years; b) the ratio of estimated impact pressure and return period is in the reck The consequence of the red zone is that the residence sbould not be at the present place. Sources of Topographic Data Mears seems to be concerned that I have not applied the best docurnentafon about the topography of the avalanche path. I wish to note that I have used the following information for the calculations of the motion of avalanches: LEWIS ~/542 a) Profile of the slope between the Taylor bu/lding and the avalanche starting zone. Beat yon Allmen and Peter Lev have observed the profile on the ground with chnometer and meamring tape in March 2003. b) Contour map of scale 1 inch = 200 feet and contour intervals 20 feet. Atpentech Inc. has pre-pared the map for LPI Holdings Inc. with date March 28, 2003. on October 12, 2004. ti) Slope profiles above the comers and the oentre of the building, observed by yon Altmen on October 13, 2004. e) Observations of Peter Lev of the ground mrfaee, estimates of the location of avalanche starting zone, and lay of the terrain in March 2003. I have referred to item~ a) and b) in my estimate, of avalanche fomes, dated April 3, 2003. I consider on-site measurements of the slope inclines, speekfioally in the Iow part of an avalanche path more informative than contour maps. Contour maps og~n do not reflect small humps and channels that d~fle~t SlOW moving avManches. In addition, I have relied on Lev's local and long-time experience ~,ith avalanches. Volume of Avalanche Snow My estimates of the volume of avalanche snow were based on measurements of avalanche dc-posits in the Colnmbia Mountains of British Columbia and the Cmaactian Rocky Mouotain~ betweeta 1966 and 1986. Becau.~e essentialty, the area, incline and roughness of the avalanche path and the amount of mow determine the avalmche volume, I do not see why maximum avalanches in Colorado should be much different. However, ifMears has better observations in Colorado, so it be. Mear~ states correctly that avalanchespick up additional mow on descent. Much avalanche snow is deposited on the low incline of the avalanche path between elevation 8000 feet and 7960 feet as well as on the road therefore it would not reach the wail. I ffddee with Meats that the space is fight and avalanche mow could spill over the w,~?- difional excavation with retaining wall or riprap boulders below the road would be D_~7,m~ary. The snow spilling over ~e wall woulcl have a low speed, would not ctarnage ~e building,~wall of the residence. Avalanche Hazard on the Road The safety of the traffic on the mad is another cqmcern. In order to make a rough estimate of the risk to tra~c on the mad, I have made the following assumptions: 3 avalanche paths (at Lotl, Lot 2, L0t3/4) with equal avalanche fi-equencies; adequate safe space between the avalanche paths for a ear stopping at an avalanche deposit. Small avalanches depositing less than 3 feet of mow on the road, Frequency once in 15 years; average width 20 feet; LEWIS 1543 // A car could be hail'buried or be pushed off the road; occupants might be injured when the car hits an obstacle, probability of death of occupants 5%. Pede~rians on the road would be pushed over and partially buried; asr~rmed probabit/ty of death 10%. Frequency once in 50 years; average ~Sdth 60 feet A vehicle might be damaged and perhaps be buried; probability of death of occupants 20%. A pedestrian would be swept offthe road and be partially or fully buried; probabit/ty of death 50%. Traffic On average during the Muter, 30 vebScles per dm)$ speed on snow covered road 15 mph; stopping did'tahoe 30 feet On average during the winter, 15 pedestrians per day (would vary much between days); walking ~eezI 3 mph. Estimated risk on Little Cloud road With my report dated October 20, 2004, t have given the avalanche hazard index, which indicates the sehousness of the avalanche hazard to road traffic. The following table contaln~ the estimated encounter probabilities between traffic and avalanches and the estimated deaths that might reralt. Encounter Probability in 1000 years . Vehicles Pedestrians Number of death in 1000 years In vehicles Pedesv~rians Small avalanches 0.17 0.16 0.008 0.01 Large avalanches 0.09 0.1'4 '0.018 0.07 Total 0.26 0.30 0.026 0.087 Comparative risks The encounter probabilites and number of deaths are rough estimates only w/th conservative ~sumptions, but they may indicate the rectitude of the hazard on the Little Cloud road. I do not have readily ava/lable statistics of comparable traffic accidents on Colorado highways, and the literature on risks usually contains only the ~umber of deaths. However, as a comparison, driving 6000 miles per year on' a highway in the Province of British Columbia has a risk of death 0.3'in 1000 years. The number of pedestrian deaths in USA, U.K. and Switzerland is between 0.05 and 0.1 deaths in 1000 years. This means, LEWIS 1544 the risk due to avalanches on the Little Cloud road is comparable mad little lower than driving and walking on any wad. Safety Measures on the Road The frequency of avalanches on the road and the tow traffic volUme do not warrant a protecton agaln~t avalanches. The hazard seems to be not worse than it is on numerous country roads. An avalanche warning, for exa,,,?le by the Colorado Avalanche Information Center, that would recommend road closures and extra caution on local roads would be u, efaL At this time, the only measure t. hat is appropriate is a sign at the road: Avalanche Danger..Do not stop on the road. Ferguson is correct in stating that avalanches would block the access to the bu/ldings on Lots 2, 3 and 4. The removal of snow and the opening of the road might be slow because snowfalls and avalanches at other ma& keep the snow removal equipment bUsy at the same time. But this would be one of the disadvantages of I/ving at the Little Cloud subd/vision. Peter Schaerer LEWIS 1545 /5