HomeMy WebLinkAbout1.0 ApplicationBAr,coMB & GREEN, P.C.
ATTOR'NEYS AT IJA\M
(FoRMERLY DELANEY & BaLcoMB, P.C.)
P. (). DRAI^/ER 79O
818 COLORADO A\TETYLIE
GITEN\MOOD SPRINGS, COLORADO 816OP
OF CoUNSEL:
KENNETH BALCOMB
JoHN A. THULSoN
EDWARD MULHALL, JR.
Scorr BALcoMB
[-AWRENCE R. GREEN
TrMorHY A. THULSoN
LoRr J. M. SATTERFTELD
EDwaRD B. Or-szewsrt
DavrD SANDoVAL
DENDY M.HETSEL
Telephone: 970.945.6546
Facsimile: 970.945.9769
November 2, L998 -" -_r i . ". B.
VIA HAI\D DELIVERY TO:
Mark Bean
Director of Planning , Garfield County
Garfield County Court House
109 8th Street
Glenwood Springs, CO 81601
Re: Lot E34. Aspen Glen
Dear Mark:
I am writing on behalf of Mr. James Gould, the owner of Lot E34 in Aspen Glen, to request
approval of an arrrended final plat of Lot E34. The purpose of the plat amendment is to increase the
size of the building envelope on this Lot.
As you will recall, Chen-Northern, Inc. did the geotechnical engineering work for Aspen
Glen in connection with the zoningand preliminary plan approval. In their work, Chen-Northern
mapped a sinktrole which extended onto the northem portion of Lot E34. After having an initial
subsoil study done for his proposed residence, Mr. Gould discovered that the building envelope was
set back an additional twenty feet beyond the sinkhole set back line designated by Chen-Northern.
Mr. Gould would now like to amend the Final Plat to enlarge the building envelope.
In support of this request, we enclose two copies of each of the
Hepworth-Pawlak Geotechnical, Inc. subsoil study for LotE34 and transmittal letter
dated October 10,1997;
Review by H.P. Geotechnical of sinkhole set back requirements dated March 30,
1998;
Supplemental subsoil study by H.P. Geotechnical for evaluation of sin}hole set back
dated June 4, 1998;
1.
2.
3.
,lrl0U 2 lges
BALCoMB & GnppIY, P.C.
ATTORNEYS AT IJAW
Mark Bean, Director of Planning November 2,1998
Page2
t 4. Letter from Louis Meyer dated July 28, 1998 regarding Lot E34 set back
requirements; and
5. Proposed Amended Plat Lot E34 depicting the enlarged building envelope.
I believe that the enclosed material adequately demonstrates that the building envelope can
be expanded as requested without violating any set back requirements within Aspen Glen and
without presenting any risk to any improvements that are constructed within the expanded building
envelope. I would therefore ask that this matter be brought before the Board of County
Commissioners at the first opportunity. I have the mylar of the proposed amended plat in my
possession and can deliver it to you signed by Mr. Gould and myself if you believe this to be
appropriate prior to the Board's consideration of this request.
Please let me know if you believe any additional information is required or if you have any
additional questions. As always, thank you very much for your attention to this matter.
Very truly yours,
LRG/bc
Encls.
BALCOMB & GREEN, P.C.
NtJv-ulJ-i>) i \4:>1 Ptf\FaRNfINCE CLTnCH I NG
I{EPIYORTH . PAI\ILAK GEOTECIf,\'ICAL, NC.
P.Zd
October 10, 1997
Jim Gould
P.O. Box 5089
Aspen, Colorado 81612 Job No. l9'l 557
Subject:Report Tra-usmital, Subsoil Study for Forudation Desigu, Proposed
Residence, Lot E-34, fupen Glen, Garfreld County, Colorado
Dear Mr. Gould:
As requested, we have conducted a subsoil srudy for the proposed residence at the
subject site.
Subsurface condidons encounered in the explorarory borings drilled in the proposed
building area consist of ibour 4 to 5 feet of flll materials overlying stiff sandy silry
clay. {elarively dense silry sandy gravel with cobbles wiui encouutered beneath the clay
at depths of |rh and 8 tbet. Groundwater was not etrcouutered in the borings at the tim,e
of drilling.
The proposed residence can be founded on spread footings placed ou the natural
subsoils-aad designed for an allowable beanng pressure of 2,000 psf. The site is
locared in a broai surface depressioo apparently cased by regional subsideuce. Th'e
foundation should be heavily reinforced to limit the effecrs of possible differential
settlements
The report which tbllows describes our exploration, sutruDarizes our f,rndings, and
presents our recommendations. It is ilnpormt that we provide consultation during
design, and field services during construction to review aad monitor the implementadon
of the geotechnical recommendatio[s.
If you trave any questionS regardiug this report, please cotrtact us.
Sincerely,
ORTH - PAWLAK GEOTECHNICAL, tNC.
NIJU-UJ-l>! / 1U:5i rtriFLrkl'IUNCE COACHiNG P. 85
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION
SITE CONDITIONS
GEOLOGIC CONDMIONS
FIELD E)CLORATION
SUBSURFACE CONDITIONS
DESIGN RECOMMENDATIONS . .
FOUNDATION AND RETAINING WALLS
FLOOR SLASS
UNDERDRAIN SYSTEM
SURFACEDRAINAGE...
LTMITATIONS....
REFERENCES
FIGURE 1 . LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND A].ID NOTES
FIGLIRE4-SwELL-coNsoLIDATIoNTESTRESULTS
FIGURE 5 . GRADATION TEST RESULTS
4
4
.)
6
,7
7
9
H-P Georecx
NL\r-YJJ-ir!/ 1Z:>j F:RFNRMFNCE COACHING P. 85
PURPOSE AND SCOPE OF STIJ:DY
This report presents the resuls of a subsoil scudy for a Proposed resideuce o be
located on Lot E-34, Aspen GIen, Garfield County, Colorado. The project sirc is
shown on Fig. 1. The pupose of the study was to develop recommendations for the
foundation design- The study was conductEd itr accordance with our agreeEent for
geotechnical engi,ueering services to Jim Gould dated September 9, 1997-
A field exploration progran consisting of exploraory borings was couducted o
obtain idormation on subsurface conditions. Samples of the subsoils obtained during
the field exploration were tested in the laboratory to determine their classiftcation,
compressibiliry and other engineering characteristics. The results of the field
exploradon and laboratory testing were analyzedto develop recommendatiors tbr
foundation ty?es, deptbs and allowable pressures for the proposed building foundation-
This report summarizes the data obtained druing this srudy and presens ou
couclusiotrs, desigu recommendations and other geotechnical engineering considerations
based on the proposed construction and the subsoil conditions encountered.
PROPOSED CONSTRUCTION
Ar the time of our srudy, design plars tbr tie residence had not been developed.
We assume excavarion for ttre buildiug will have a maximum cut depth of one level,
abour 10 feet below the existing ground surface, For the purpose of our analysis, we
alisume that the residence will be a two story wood frame structure over a crawlspace
or basemenr fouudation. Loadings for the sEuctue were assumed to be relatively light
and typical of the pr:oposed type of consmrction-
If building location. grading and loading information are significandy different
than assuned, we should be norified to reevaluate the recommeudations presented in
this report.
NUU-6J-1>: t 16:>4 FERFDRNANCE CORCHING
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P.A7
srTE cOil[DmONS
The site was vacant at the time of our field work. The ground surface is
relatively flat with a very stighc slope down to the south-southeast. There is less thaa
about 1 foor of elevation diftbreuce in the area of the building envelope. A moderate
slope exists to the southeast of the lot down to the golf course. Vegeation consists of
grass and. weeds.
GEOLOGIC COI{DTNONS
Bedrock of ttre eennsylvuria age Eagle Valley Evaporire underlies the Aspen
Gles Club. These rock are a sequence of gypsiferous shale, fiue-grained
sandstone/silstone with some massive beds of glpsum and limestone. There is a
possibiliry rtrat massive, heavily bedded glpsum deposits associated with the Eagte
Valley Evaporite underlie porrions of the lot. Dissolution of the glpsum under certain
condirions can cause sinkholes to develop and produce area of localized subsidence.
Dlring previous work in the area, several broad subsidence areas and smaller size
sinkhole areas were observed scatered throughout the Aspen Glen Club (Chen-
Northern, 1993). The sinktroles appear similar to others associated with the Eagle
Valley Evaporite in arpas of the Roaring Fork Vailey. The broad subsidence aPPeared
to be on the order of 5 feet relative to surrounding areas'
Lot E-34 is located within one of these broad subsidence areas and an existing
sinkhole is located ro the norrh of the building eovelope which has since beeo
baclrf,rlled. The building .nv.lop. is setback from the sinkhole according to the
recommendarions by Chen-Northern. No evidence of cavities-was elrcountered in the
subsurface materials during our study. However, the exploratory borings were
relatively shallow, for foundation design only. Based oo our preseff knowledge of the
subsurface conditions at the site, it canuot be said for certain that gradual subsidence or
sinkholes will not develop. The risk of ground subsidence in the buildiug envelope of
NLJU-6J-i>> I J.d; )q PExi-ukilHNLe CUIICH I NG P. 88
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Lot E-34 throughout rhe service life of the proposcd resideoce is mapped as moderate
and the owner should be aware of the Potential for ground movemeot'.
NELD EPLORATION
The freld exploration for the project was conducted on September 11, L991-
Two explorarory borings were drilled at the locations shown on Fig. 1 to evaluate the'
subsurface conditions. The borings were advauced with 4 inch diameter contitruotls
flighr augers powered by a crack-mounrcd CME45 drill rig. The borings wer€ logged
by a represenative of Hepworth-Pawlak Geotechnical, Inc'
Samples of the subsoils were taken with I% inch and 2 inch I.D. spoon
samplers. The sampler, ,".r. driven into the subsoils at various depths with blows
from a 140 pound hammer falling 30 inches. This test is similu to the s6ndard
peretration tesr described by ASTM Method D-1585. The penetation resistance values
a.re ar indicadon of the relarive density or consistency of the subsoils. Depths at which
rtre samples were takeo aud the penetration resistance values are shown on the Logs of
Explorarory Borings, Fig. 2. The samples vrere returned to our laboratory for review
by the project engineer and testing.
SI,'BSURFACE COI{DITIONS
Graphic logs of the subsurt'ace conditioru encountered at the site are shown on
Fig. 2. The subsoils consist of about 4 to 5 feet of fiIl materials from overlot gradiog
overlyisg sriff saldy silty clay. psfigivel] deuse silty surdy gravel sentaining cobbles
and possible boulders was excavated beneath the clays at deptbs of ]th aud E feet'
Drilling in the dense gravel with auger equipmeng was difiicult due o the cobbles and
boulders aad driuing refusal wa,s encounrcred in the deposit.
Laboratory testing performed on samples obtained from the borings included
natural moisture content and densiry and gradation analyses. Resuls of swell-
cousolidation testing pertbrmed oo reladvely und'sturbed drive samples of the clay,
, E:F 6E5iEcil
Nuu-tslJ-l>, / id: )4 tstxFIJkHFNLE LUBCHiNG F. A9
4-
presenred on Fig. 4, indicate low to moderate compressibiliry uuder cooditions of
loading and wening. One sample showed a minor expaasiou Poteotial when wened.
Resuts of gradation analyses performed sn 5mell diameter drive samples (minus 1%
inch fraction) of the natural coiuse granular soils are shown on Fig. 5. The laboratory
testing is summarized h Table I.
No free water was encountered in the borings at the time of drilling and the
subsoils were slightly moist to moist.
DESIGN REC OMMEI{DATIONS
FOUNDATIONS
Considering the iubsoil conditions encounrcred in the exploratory borings and'
tre naure of the proposed coffitruction, we recommend the building be founded with
spread foodngs bearing on the nanral subsoils. The foundation should be heavily
reinforced to limit the effecrs of possible differential settlement.
The desigu and construcdon criteria preseuted below should be observed for a
spread footing foundation system'
1) Foorings placed on the uudisturbed nahrral soils should be designed for
an allowabte soil beuing pressure of 2,000 psf. Footings placed eDrirely
oo the lower dense gravel subsoils can be designed for an allowable
bearing pressure of 3,000 psf. Based on experience, we expect
seffleqent of footings desigued aad cousructed as discrxsed in this
section will be about I inch and could be differential bepeen footings
bearing on the clay and the gravels'
Z) Thc footiags should have a mrnl+um width of 16 inches for continuous
walls and? feet for isolared Pads'
3) Exrerior footings aud footings beneath unheated areas should be provided
with adequare soil cover above their beariog elevation for frost
NLJv-€i-i>5 i id: ))rr,RI-UKNiNCE CONCH i NG o rDI . IU
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protection. Placement of fouudadors at least 36 inches below exterior
grade is rypically used in this area.
Continuous foundatiou walls should be reinforced op and bottom to span
local anomalies such as by usunoing an unsupported tength of at least
t4 feet. Foundation walls acting 2S retaining strucures should also be
designed to resist lateral earth pressues as discussed in the "Foundatioo
ssd f,sreining Walls" section of this rePort.
AII existing fill, ropsoil and any loose or disnubed soils should be
removed and the footiog bearing level extended down to the firm nailral
soils. lf water seepage is encountered, the footiug areas should be
dewatered before concrerc placement.
A represeutative of the geotechnical eugineer should observe all foociog'
excavarions prior to concrete placement to evaluate bearing condirions.
FOUNDATION AND RETAINING WALIJ
Foundation walls and retainiug structures which are laterally supported aad can
be expecred to undergo only a slighr amount of deflection should be desigued for a
laeral earth pressure com.pued ou the basis of an equivalent fluid unit weight of 50 pcf
for backfill consisring of rhe on-sire clay soils. Cantilevered retaining structures which
are separare from the rxidence and can be expected to deflecl sufticiently to mobilize
the full acrive earth pressue conditiou should be designed for a lateral eanh Pressure
computed on the basis of an equivalent fluid unit weight of 40 pcf for backfill
consisting of the ou-sip soils. Backfill should not cortai!. vegehtion, topsoil or
oversized rock.
AII foundarion and retainiog sfucrures should be designed for appropriate
hydrosatic an6 surcharge pressures such as adjacent footings, Eaffic, constnrcdon
materials and equipment' The Pressures recommended above assume drained
cooditions behisd the walls and a horizoutal backfill sruface. The buildup of waEr
behind a wall or an upward sloping backfill surface will increase the lateral Pressure
4)
5)
5)
NLrV-ElJ-i>: r 1d; >)FERFUKNNNCE CDFCHING P. 1l
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imposed on a foundation wall or retahing s!ructure. Au underdrain should be provided
to preveut hydrosatic Pressure buildup behind walls'
Backfill should be placed in uniform lifu and compacted to at least 90% of the
maxiruum standard Proctor density at a Boistue content near optimulD'. Backfrll in
pavemeur and walkway areas should be compacted to at least 95% oI the ma;cimuo
standard proctor densiry. Care should be taken Bot ro overcompact the backftll or use
large equipment near the wall, 5i11ss this could causi excessive lateral pressure on the
wall. Some sertlement of deep foundation walt backfill should be expected, even if the
material is placed conecrly, aud could resulr in distrqss to facilities constructed on the
backftll.
The lareral resistance of foundation or reaining wall footings will be a
combination of rhe slidini resistance of the footing oo the foundation rnaterials urd
passive earrh pressure against rhe side of the footing. Resisance to stiding at the
bottoms of the footings can be calculated based on a coefficient of frictiou of 0.3 for
rhe clay soils and 0.45 for the gravel subsoils. Passive pressure of compacted backf,tll
against the sides of the footings can be calculated using an equivalent fluid unit weight
of 350 pcf. The coefficient of fricdon and passive pressue values recomnended above
assume uldmate soil srengrh. Suitable factors of safety should be included in the
design o timir the srrain which will occur at the uldmate strength, panicularly in the
case of passive resisance. Fill placed agailsr the sides of the foodngs to resist lateral
loads should be compacted to at least 95% of the ma,rimum standard Proctor densiry at
a moisure conrent near oPtimum.
FLOOR SLABS
The narural on-site soils, exclusive of existing fill, are suitable to support lightly
loaded slab-oo-grade construction. Slabs placed on the upper,comPressible clay soils
could experieuce some posr construction slab movement. To reduce the effeca of some
differential Eovemetrt, floor slabs should be separated from all beariug walls and
columrs with expansion joints which allow uurestrained vertical movemert- Floor
slab control joins should be used to reduce damage due to skinkage cracking. The
1!. ve T arr-unt irrfstr \-uHtnlNLl P. L2
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requiremenrs for joint spacing and slab reinforcement should be established by the
designer based on experience and the intended slab use. A mirrimum 4 inch layer of
flgg-fueining gravel should be placed beneath slabs to faciliate drainage. This material
should cousist of minu 2 inch aggregase with at least 50% retained on the No. 4 sieve
aud less than}% passing the No. 200 sieve'
All ru materials for support of floor slabs should be compacted to at leuit95%
of maximum standard, Procbr densiry at a moisture conrcn[ uear oPligum. Required
fill can consisr of the on-site soils devoid of vegetatiou, topsoil and oversized rock.
UNDERDRAIN SYSTEM
Although free water was not encounered during our exploration, it has been our
experience in mounrainous areas that local perched groundwater may develop during'
times of heavy precipitation or seasonal runotf. Frozen ground during spring runoff
can create a perched condition. We recommend below-gnde constuction, such as
ygtaining walls, crawlspace and basement areas, be prOtected from wefting and
hydrostatic pressure buildup by an underdrain system'
The drains should consist of drainpipe placed in the bottom of rhe wall bacHill
surrounded above the invert level with free-draining graoular material- The drain
should be placed at each level of excavarion and.at least 1 foot below lowest adjacent
finish grade and sloped at a minimum l% to a suitable gravity outlet. Free-draining
grauular maerial used in the underdraiu system shoutd conain less than 2% passing the'
No. 200 sieve, less than 50% passing &e No. 4 sieve a-ud have a ma:rinum size of
2 inches. The drain gavel backfill should be at least 1% feet deep'
SURFACE DRAINAGE
The followi4g drainage precautions should be observed during consErrction and
mainained at all dmes afrer the residence has been completed:
l) Inundatioo of the fouudarion ercavatiofft aud underslab areas should be
avoided during coustructiou'
NUU-ui-1:i'l 1Z:5o FERFORflRNCE CORCHING P. 13
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Exterior backfill should be adjusted to neal optimum moisrure and
compacted to at least 95% of rhe maximum sa-Bdard Proctor density in
pavemeng and slab alea5 and to at least fr|o Of the matimum standard
Proctor densiry in landscape areas.
The ground surface surrounding the extcrior of the building should be
sloped to drain away from ttre foundation in all directiors. We
recommend a minimum slope of 5 inches in the first [0 feet in unpaved
areas and a minimum slope of 3 inches in the fust 10 feet in paved areas'
plse-drxining wall backfill should be capped with about 2 feet of &e
on-site fine-grained soils to reduce surface water intjlration.
Roof d.ownsPouts and drains should discharge well beyond the linits of
all backfili
LITIITATIONS
This srudy has been conducted is accordance with generally accepted
georechnical engineering principles and practices in this area ar this time' We make no
waffarty eirher expressed or implied. The conclusions and recommeudations submitted
in this report are based upon the data obtained from the exploratory borings drilled ar
the locatiors indicated on Fig. l, the assumed rype of construcrion and our experieuce
in the area. Our findings include interpolatiotr and extraPolation of the subsurface
conditions identified at the explorarory borings and variadons in the subsurface
conditioru ',ay
nol become evident until excavation is performed. If conditions
encouEtered during coNtrucrior appe,u different from those described in this repon,
we shoutd be uotihed so that re-evaluation of the recommendations rnay be made.
This report bas been prepared for the exclusive use by- our client for design
purposes. We are not responsible for technical interpreUrions by others of our
informatiou. As the projecr evolves, we should provide continued consulEtion atrd
6eld services during construction ro review and monitor the implemenEtiotr of our
recornmendations, and to verifu that the recommendations have been appropfiately
2)
3)
4)
r\uv-6J-i,>>( L4.>(PERFDRNRNCE CUrrChiNG O aA
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interpreted. Significant design cl6trges may require additional analysis or
modificatiogs ro the recommendatioos presented herein. We recommend on-site
observation of excavations and tbundarion bearing suata and testing of skucnfal fill by
a representative of ttre geotechuical eugineer-
Sincerely,
REFERENCES
Chen-Northern, Inc. lgg3, Geotechnical Engineeing Stuty for Preliminary Plat
Design, ,4spen Glen Dqelopment, Gafield County, Colorado, prepared for
AspenGlenCompany,datedMay2E,tgg3'JobNo'4ll2y2'
Chen-Northeru, Inc. 1991, Prelimirury Geotecltnicat Engineeing Stttdy,Proposed
nprn dten Deuelopment, Gatfietd Cortttty, Colorado, prepared tbr Aspeu Glen
Compa-uy, dated Deccmber 20, 1991, Job No' 4 fiLn'
P. 15
APPROXMATE SCALE
1'= 30'
GOIJ
COURSE
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,-.r-.-.-.-.-r_r_......i...,.,.,
EDGE OF
SINKHOLE
SETBACK
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LOT E 35
GROUND AT PROPERTY
= 100.0', ASSUMED.
BENCH MARK:
CORNER ELEV.
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LOCAT1ON OF EXPLORATORY BORINGS197 5s7 HEPWORTH - PAWLAK
GEOTECHNICAL. INC.
TnTrrr o l<
Herwo Rrtl-p6rvt.e,x GroTsctlNlcAL, INc-
lvlarch 30, 1998
Jim Gould
P.O. Box 5089
Aspen, Colorado 8l 612
-fr ur :O r-.ql' r\q.l.,r(-.rf f.02
5ur0 Rorrl 191
Clcnwood Sprln3r, C() 81501
Fex 970 945.8^15.1
Phonc 970 945.7988
Job No. l9'7 557
Subject: Geotechnical Review of Sinkhole Setback Requirements, Proposed
Rcsidcnce, Lot E-34, Aspen Glen, Gartield County, Colorado.
Dear Mr. Gould:
As requested, we have revicwcd thc geotechnical conditions described by Chen'Northern,
Inc. in thcir report preparcd for Aspen Glen Company dated May 28, 1993, Job No.
411292. The pulposc of tlre review was to compare the location of the building envelopc
with respect to sinkhole setback requirements. Hepworth-Pawlak Cieotechnical, Inc.
previously conductcd a subsoil study for the lot and presented our findings in a report
datcd October 10, 1997, Job No. 197 557.
Proposed Con.struction: We understand that you would like to cnlarge the building
envclope cltrser to thc sinkhole arca, We are not aware of dcvclopurent plans for thc lot
but assume the single farnily residcnce will be 2 to 3 storics of wood frame constructiotl
over B crawlspace or basemcnt level.
Gcotechnical Conrlitions: ChenNorthcrn had rnapped a sinkholc that extends into the
nr:rthcm psrt of Lot. E-34. An exploratory boring 8-3-93 was drillecl aud a trenchT'z'gz
was excayarsd to evaluate thc sinkholc. I'he boring cncountered I I feet of sandy silty clay
overly.ing silty sandy gravel with cobbles. Groundwater was meusured at a depth of 30%
feet in thc boring. Based on the results of thcir study, a setback line was recommended
beyond which buildings and utilities ct>uld be constructed with prccautions for possible
ground movcment.
Conclusions: Thc sinkhole area which includes the setback distance, and the building
cnvelope as providecl by Schmueser Gorrlon lvlcyer, Inc. is shown on Fig. l, attachcd.
Based on our rcvicw the current building envelope is setback about an additional 20 feet
from the sinkhole setback linc designated by Chcn-Northern,lnc. Assuming the SGIvI plan
!!! !eerr l!q'vvw )aJ orJq iPr v( )a 14 No.u05 P
Jim Gould
March 30, 1998
Page 2
is accurate, the building envelope can bc cnlargcd about 20 fcct to thc north. If this is
proposed, we should drill at lcast onc additional boring at the proposed new building
envelopc line for geotechnical conditions. We also recommend that SGM review their
drawings to verifo the accuracy of the Chen-Northern setback line on the plan provided to
us.
If you havc any questions or require furthcr assistance, pleasc call our oftice.
Sincerely,
I{EPWORTH-PAWLAK GEOTECHNTCAL, lNC.
Jordy Z. Adanrson, P.E.
Rev. by: SLP
JZNro
attachment
Rcfcrcncc:
Chen-Northern, Inc., Geotechnical Engineering Studyfor Preliminary Ptat Design,
Proposed Aspei Glen Developmen, Gufield county, colorado, May 28, 1993,
Job No. 4ll2 92, prepared fior Aspen Glen Company.
UI le....J l\0,uu)
APPROXIMATE SCALEl" = J0'
SINKHOLE
SETBACK
GOLF
COURSE
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OTa
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POSSIBLE \
INCREASE
IN BUILDING \AREA
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BENCH MARK:
CORNERI ELEV.
LOI E 35
GROUND AT PROPERTY
= 100.0', ASSUMED.
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HEPWORTH - PAWLAK
GEOTECHNICAL, INC.LOCANON OF EXPLORATORY BORINGS
r::rukflFNLi CDriCh I NG
H Errl'<-rRTn- P.rrv L,tK C r cl r e curu I cr\ L, I N c.
June 4, 1998
P. 82
?r-010 R,'.rri I il
Clcnwuorl Spring>, CU rl601
F,rr 97tJ 9l-c.Hil
Phonc 970 9{5-79lts
Jim Gould
P.O. Box 5089
Aspen. Colorado 81612 Job No. 19i 557
Subject: Supplemental Subsoil Srudy fbr Evaluarion trf Sinkhole Setback.
Proposed Residence, Lot E-34. Aspen Glen. Garfield Counry, Coloraclo
Dear Mr. Gould:
As reErested, Hepworth-Pawlak Geotechnical, Inc. performed addirional subsurface
exPloration evaluate the feasibiiity of building closer to the sinlfioie ar the zubject sire.
{egworth-laylak Geotechnical, Inc. previously conducrcd a subsoil snrdy in rhe
lesignated^building_enve_lope of the lot aud preseuted our findings in a reporr dated
October 10, 1997. Job No. 197 557 . We later conducted a geoGcbnical ieview of rhe
sinkhole setback requiremonts on the lot and prcsened our findings in a letter dated
March 30, 1998, Job No. L97 557. The current work was conduited as a supplemenr to
our previ<lus itudy.
hoposed Construction: Plans for the proposed. residence hacl oot been developecl ar rhe
time of this srudy. We understand that our tindings will be considered in the
sale/purchase a-srecmcnt of the property. Wc assume the single faAily will be 2 n 3
stories of wood frame construction over a crawlspace or basement level. Cut depths are
assumed to range berween about 4 to I feet,
Subsurface Conditions: Ihe subsurface conditions outside the present building
enveiope were evaluated by drilling two adclirional s1pt61xrory borings at the
lPProximate locations shown on Fig. l. The logs of the borings are pre.sented onFig.2. The subsoils encounrered, below about 6 feer of fill. consist of stif sandy silry
clay overlying medium dense silry sandy gravel conririning cobbles and boulders ar
depth.s of 13 and 14 feet. The gravels at Boring 2A appeared less den.se than tho.se
cncountered at Boring lA and Borings 1 and 2. The clay layer was about 5 t'eet thicker
at Borings 1A and 2A compared to Boriugs I and 2. Resulrs of swell-ct'rnsolictation
i.ttiog performed on a relatively undisturbed sample of the clay, presented on Fig. 4.
indicate moderate compressibility under condirions of loading and weniog. No fiee
water was encountered in the borings at the time of driliug and the soils were moisr to
very moist.
Contlusions: The subsurface profiles encountered in the addirional borings are sim.ilar
to those.of our previous study excep! that the clay depth is much grearer ind rhe gravei
densitv'is lower. These differencei could be due to the prior sinkhole activity on thelot. Enlargement of the envelope closer ro rhe recomrnended setback proviOea by Chen-
Northern, Inc. and in accordance wirh our review of lvlarch 30, 199g appears
acceptable. Due to the variahle subsurface conditiors, there could be an-increase indiffereatial settlenrent potential between the shallower and deeper clay areas.
Con"sideradon should be given to use of a mat foundation ro timir rhe porential
seitlement and disuess due to the subsoil and -eeolo-eic conditions. Thi rEcr:mmendatioos
F. B]
Jim Gould
Junc'4. 1998
Page 2
prcsented in our previous repoil should be considered pretiminary ancl thc geotechnical
engineer shtluld review the proposed development plan prior to construcripn.
Lirnitations: This study has bcc-n conducterl in accordance with generally acccpced
geotechnical engineering principles aud practices in this area er rh-is rime. We make nowarr:Inty either expres.sed tlr implied. The conclusions and recomnrendatit)ns suhmitted
in this repom are trased upon the data obtained tiom rhc explorartrry horinss rlrilled at
the location.s indicated on Fie. I and to the tlepths shown on Fig, i. rhe a-i.surned rype
of construction. and our expericnce in the area. Our findings incturJe interpolation and
exrrapolatitrn of the subsurface conditions i,Jentitied ar the e--rplorarory borings andvariations in the subsurfhce conditions rnay no( bccornc evirlent until excavaion isperformed. If conditions encountdred du.ring construcriou appear difrtrenr from those
described in this report. we should be notified at ooce so re-&aluarion of rhe
recommendations may be made.
This report has been prepiued tbr the exclusive use by our clienr for design purposes.
We are not responsible for technical interpretations hy others of our info-rmition. es
the project cvolves, we sh<iuld provide cootinued consultation and field services during
constnrctitrn Lt: review and moniror rhe implementation of our recommendations. and toverify rhar thc rcconunendations have becn appropriately inrcrprered. .Signillcanr tlesign
chan-ses mav require additittnal analysi.s r:r modificar,ion.s ro rhl recqmmendatiqns
presented herein. We recom:nend on-site observatiou of excavations and tbunclatiorr
bearing strata and testing of .strucrural fill by a repre.senrative ol rhe ger:technical
engineer.
If -vou have any questions or if we may he of further assistance, please let us know.
Sinccrely,
- PAWLAK
${iii;;i#o ci'T O\.t15707 5!
s,,ffi#
,h4,L
Stevgn L. Pawlali, P.E.
JZAlksm
atuchments
H-P GEOTECH
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APPROXIMATE SCALE'l' = 30'
LOT E 34
ozo
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--
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BUILDING
LEGEND. BORING
O BORING
STUDY
EaseA/E^F - >\--f
LOT E 35
BENCH MARK: GROUND AT PROPERTY
COnHEn; ELEV. = 1OO-0'. ASSUMED'
DRILLED FOR THIS STUDY.
DRILLED FOR PREVIOUS
12/11/e7.
\
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LOCAI]ON OF EXPLORATORY BORINGSHEPWORTH - PAWLAK
GEOTECHNICAL, INC.197 557
c,
0,L
I
cq
,'
o
IJ
BORING 1A
ELEV. = 100.0'
BORING 2A
ELEV. = 100.1'
rc/ai2/2
2E/12
16/12
llC=26.7
D0=98
17 /3,7 /o
Note: Explonotion of symbols is shown on Fig' 3'
ooL
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-9lrl
2e/12
26/12
LOGS OF EXPLORATORY BORINGSHEPWORTH PAWLAK
GEOTECHNICAL. INC.197 557
ffi
n
W
LEGEND:
flLL: cloyeY sondY grovel,with cobbles qnd boulders' medium dense, moist, red'
CLAY (CL): silty. sondy, stiff, moist to very moist' red'
GRAVEL (GM); silty, sondy, with cobbles ond boulders, medium dense to dense. slightly moist,
reddish brown.
Relotively undisturbed drive somple: 2-inch l.D. Colifornio liner somple.
Drive somple; stond-ord penetrotion test ( spr )' t s'la-inch l'D' split spoon somple' ASru D - 15E6'
Drive somple blow count: indicotes th_ot 15 blows of o 140-pound hommer folling 30 inches were
required to drive the Colifornio or SPT sompler 12 inches'
Procticol rig refusol.
NOTES:
,. Explorotory borings were drilled on April 27, 1998 with o 4-inch diometer continuous flight power ouger'
2. Locotions of explorotory borings were meosured opproximotely by pocing from feotures shown
on the site Plon Provided-
3. Elevotions of explorotory borings were meosured by instrument level ond refer to the Bench Mork
shown on Fig. 1.
4. The explorotory boring locotions ond elevotions should be considered occurote only to the degree implied
by the method used.
5. The lines between moteriols shown on the explorotory boring logs represent the opproximote boundories
between moteriol types ond tronsitions moy be groduol'
6. No free woter wos encountered in the borings of the time of drilling.
Fluctuotion in woter level moy occur with time'
7. LoborotorY Testing Results:
WC:WoterContent(Z)
DD = Dry Density ( pcf )
F
i
16/12
LEGEND AND NOTESHEPWORTH PAWLAK
GEOTECHNICAL, INC.197 557
Moisture Content = 26-7 Percent
Dry Density Weight = 98 Pcf
Somple ofi Sondy CloY
From: Boring 1A of 8 Feet
N
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0
1
2
3
4
5
6
7
APPLTED PRESSURE - ksf
SWELL-CONSOLIDATION TEST RESULTSHEPWORTH PAWLAK
GEOTECHNICAL, INC.197 557
\,GM-118 West 6th. Suite 200
Glenwood Spnngs, CO 81601
lcrfiu€5rnooeot,flfiYEt
.luly 28, l99t
lan Haas
Aspan Glen Golf Co.
9929Hwy.82
Carbondale, CO t1623
RE: Lot E 34 Aspen Glenn/Set'backRequiremcnts
Dear Ian,
Thc purpose ofthis lener is to commetrt on the building envelope for Lot E-34 at Aspen GlerU first
final plar As you know, [IPGeotech identified a sink hole in the vicinity of Lot E'34. Based upon
their original set-back rcquircments druing the land use prcccss with Garfield Couaty, "
6ui[ding
cnvelope was pepued which avoided the sink hole. Subscqn€nt to 6e preparuion of the fr:ral plat,
Hepworth-Pawlak has preparetl additional geotechnical work to better refine the set'back
requirement for this lot.
I am in receipt of rcport dated Jrue 4. 1998 which further considers the set-backs for this lot. It is
rny interpraation ofthis report that an enlargement ofthe Lot E-34 building eavelope is accepuble.
Figrue I of the report shows the enlargement of the lot.
'Fhe cnlargernent of the building envelope will not iopact a.uy of the other civil cngineering issues
i-e. access, water and sewer service, or drainage.
A plat amerdmeot or modification will be required to adjut the building envelope. I will work with
Ken Wilson of otu office to prcpare $at document. If you have any questions or comncnts please
don't hcsitate to call.
Sincerely,
SCHMI.JESER GORDON ME\re& TNC.
/flfu-*-
Louis Meye6 P.E.
l-OM:aib:91O2tfi5
cc: KenWilson, SGM
.luly 28, 1998 (rn r,'i3on - ''1t'., i'
lur Haas
Aspan Glen Golf Co.
9929 Hwy.82
Carbondde, CO t1623
RE: Lot E 3,l Aspen Glenn/Set'backRequiremcnts
Dear Ian,
The pulpose of this lener is to comment on the building euvelope for Lot E-34 at Aspen Glen, fiIst
fina]-plar As you know, [IPGeotech identified a sink hole in the vicinity of Lot E'34- Based upon
their original set-back requirements druing the laod use prcccss with Garfield'Couaty, a building
cnvelope *as pepared which avoided the sink hole. Subscquent to 6e preparation of the final plat,
Hepworth-Pawlak has prcparetl additional gcotechnical work to better refine the set'back
requirement for this lot.
I am in rcceipt of rcport dated June 4. 1998 whioh furttrer considers the set-backs for this lot. It is
my intepretation of this rcport rhat an enlargement of the Lot E-34 building eavelope is accepuble.
Figure I of the report shows the enlargement of the lot.
'Ihe cnlargernent of thc building envelope will not impact any of tbe other civil engineering issues
i.e. acccss, water and sewer sewice, or &ainage.
A plat amendmeat or modification will be required to adjrst the building envelope. I will work with
Ken Mlson of ou office to prepare that document. If you have any questions or commcnts please
doa't hesitate to call.
Sincerely,
scHMr.iEsER GORDON MEIaE& rNC.
Louis Meyer, P.E.
l-OM:rib:93qlt4oi
cc: KenWilson, SGM