HomeMy WebLinkAboutB15-0199_Geological report_1434050400.pdfoo
Dominic F. Mauriello, AICP
BAI/Braun Associates, lnc.
P.O. Box 2658
Edwards, Colorado E1632
oo
Courns & AssctATEs
6eorccrcr em Nln a Rf€ornc CoilgJlrrms
P.O. Box 23 - 1116 tAnreore DRrrc
Sur, Ca.on^Do 81652
Pxo|{e/Fp< (97O) E76-W
bocolerof.nct
July 17, 2000
R.obert Selby
4380 N. Campbell Ave. No. 2fl)
Tucson, fuizona 95219
_ - RE: .tqr !, Uo{sruDcE SuBDtvrsroN FtuNc No.4
Gentlemen:
At Mr. Mauriello's request I have examined the subject property for the purpose of evaluating potential
geologic hazards to the tract, and the effects of mitigating such hazards as may exist on a_djacent
properties, in accordance with Tovvn ofVail Regulations Chapter 12-21-15. The propertywas the zubject
of a previous investigation and report dated December 4, 1990, by Dr. Nicholas Lampiris; it is biing
reexamined in light of the proposal to subdMde the parcel into two lots, general$ in accordance with
the conceptual site plan provided by Mr. Mauriello. According to this plan, the two lots are located near
the northeast end of the parcel, with a driveway extending northeasterly from the. existing culdesac at
the end of.Aspen Grove Lane.
Lot 8 itself consists of a moderately-steep slope (up to 2fl along the southeast side, a bench area
through the center ofvarying widtl with slopes from flatto less than l0o, and bedrock slopes up to the
northwest generally between 20o and a maximum of 30". The lower outslope consists of glacial drift
composed ofcobbles and boulders ofvarious rocktypes in a matrix of silt and sand. These materials are
generally quite sable, although care must be taken to arroid saturating them, especiallywhere disturbed
by cuts or excavatiom. The bench itself is the result of resistant ledges of upper Minturn Formation
sandstones and limestones. The contact between the Penngilvanian Minturn and the overlying Maroon
Formation of Pennsylvanian - Permian age occurs along and near the northwest boundary of the
proPerty; theupper slopes consistof'rcd Maroon silstenes, sandsCones.aodshales, with some{imestong-- - - -
exposed ledges ofwhich can be seen especially above proposed lot 2. These slopes also appear to be
stable. The nrro proposed building envelopes as shown on the conceptual diagram occupythe relatively-
level bench toward the northeast end ofthe tract, while tlre driverray dimbs from Aspen Grove lane onto
the bench through a surale in the center.
The conceptual lot and access locations appears to be the best possible, taking full 3dpntage ofthe
existing topography. The building envelopes are located on verygently-sloping to nearly-flat land, while
the drivalay will curve up and through a gap in the Minturn Formation ledges, thereby minimizing
Potendal rock work. As originally recommended by Dr. lampiris, excavations that are required into
hillside slopes should be supported by engineered retainingwalls, lfhillside excavations are requiredfor sFucnrre foundations, those foundations should be designed accordingly. Eecause of the
unconsolidated glacial drift that composes the slope below the envelopes, landscapingshould be limited
to the extent possible to native vegetation that does not require supplemental irrigation. All drainage
should be designed and constructed in such a manner as to prevent saturation ofthese materials.
aO OO
Page2
Both conceptual envelopes lie within the medium-severity rockfall zone as shovrn on the Tovm of Vailgeologic hazard maps. The hazard is present in the form ofthe slopes noted above and rock ledges ofthe Minturn and Maroon Formations on these slopes. The beds that make up these ledges dip ge;rallynorth, into the hillside, and bedding is such that fragments that do break odare usually slabi oi blocks,whichdonottendtorollfardowntheslopes. Slopevariationsandvegetationfurtherieducetheactual
roctdall hazard, although it is certainly not nonedstenL One or rnore "normal. rocldall mitigationmeasures such as raised and strengthened foundations, timited openings on the uphill side ofstructures,
berms or rock walls, landscapegrading, structure orientation, ani to oi.t may be recommended on a site,specificbasis once building ervelopes are established with certainty and conceptual buitding designs areavailable. Extraordinary mitigation requirements are not anticipated.
While the site area is not included in arry of the Town ofVail's snow avalanche hazard zones, because oftie moderately-steep slope there is tlre remote possibility of smatl slab-type slides after unusually heany
snowfall, and snow-rolls, or "doughnuB," arc also a possibility. Mitigating measures for rocldall tlrat may- '-be requireddependinSonSnal-enrdepe.-loedion€nd{€nceptual stFuchrredesigpshould-also provid! .-
adequate protection against either phenomenon.
The necessity for proper drainage has been noted. Soil testing should be sufficient to locate near-surface
bedrock areas, if any, and foundations and perimder drainage should be engineered accordingly. Vrrhile
soils and bedrock materials found in the area do not ordinarily contain radioactive minerals, inhabited
structures should as a matter of course be designed to preclude radon gas accumulation. Ukewise, the
Vail area is one of many faults, some ofthem of significant displacement, and as a result, although there
has been no movement on these structures for thousands of years, inhabited structures should be
designed and constructed according to the Uniform Building Code provisions for Seismic Zone l.
The site is in an area of modest geological sensitivity, and sitespecific mitigating measures are notanticipated to be significant, The proposed building envelopes and actess road are as wel l-located relative
to existingtopography and recognized geologic hazards as possibte. There is nothing to suggest thatthe
proposed subdMsion or potential site specific hazard-mitigating measures that might be required will
increase the hazard to other property or structures, or to public buildings, rights-oFway, roads, streets,
easements, utilities, or facilities or other properties of any hnd. This report is intended to comply with
appropriate portions ofTovvn ofVail Regulations Chapter 12-21-15, and nothing contained herein should
be interpreted as suggestingthatthe zubjectproperty is noto(posed tothe mapped hazards. lfyou hwe
any questions or require any further information, please do not hesitate to concrct me.
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or failul of inptoPert €trgirccli.d, conragtad, ard/or B.itielned ntommcodcd Dfigrtions, o( oitigsdoN tft h r b.cn rltcred in eny vey rduroewriiontiose Econncnded by thc pr€p&!r.
Bruce A.
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mr0 DEC 1 31990
Rtrnal.d lrl. ltobinet-teRobinelte Architect
1941 Nsrl:lr C,empbet I'i lrgcon AZ ElYj7 Lrl
lifl:: Flarar-cl lila]tu,rti.
lcholas Lamplris, Ph.D.
CONSULTING GEOLOGIST
0793 VALLEY ROAD
CARBONDALE. COLORADO 816?3
(3031 6i13600 (24 HOURS)
Dec enrb err 4 . :i c/9O
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