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Koechlein Consu�t�ng Eng�neers, �nc.
�� Consul�ing Geo�echnical Eng �neers
' � "�2364 W. Alameda Pkwy • Su�te 1'�5 • La�Cewood, C4 80228-2845 ,
www.KCE-Denver.coin
LAKEWOOD AVONISILVERTHORNE
(3D3) 989-1223 (970) 9�49-6009
(303) 989-0204 FAX (970) 949�9223 FAX
November 17, 2006
i Toi�.i Kassinel
' Town of Vai1 Pul��ic Worlcs
1309 Ell�zorn DF7ve
Vai1, CO 81G57
SuUject: Dewaterillg/Settleinent Estiinate Review
Pro�osed r'our Seasons Resort
Vail Road and Soufll I'rontage Road West
. Vail, Colorado
Job No. OG-130
As requested we rev:iewed the infoi�nation provided for tlie dewatei-�ng for the sulaject site and
� settlei��ent esli�nates for adjacent �uildings. T11e �ui�ose of tlus Ietter is to �rovide our
! cox�clusians iii regai•ds to the�ro�osed dewatering and sEttleillent calculatiolis.
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' He�waztl�-Pawlalc Geotechnical (H-P) X�erfoiYned a subsurface investigation and p�-esez�ted tl�.e
z�esults i�.tlae repol�: Geoteclulical �ngii�eei-ing Study, Job No. 105 29I, dated Jua�.e 22, 2005. The
suUsuiface conditions enerall co�sisted of 3 to 11 £eet of -aiiular fIl underlain b �elativel
� Y b'� Y Y
� dense, �uatifed szl�y sand az�d g,�•avel cozitaining occasional zones of cobl�les and boulders. Silt
Y
sand lenses, varyil�g fioz�.�. 2 to 11 feet thick, were occasionally encounte�•ed. Tlze �ropose�
dewaterii7g sysieill l�as bee1�pxe��aa-ed�y Gz�.ff zi Dewaterii�g, LLC (Griffin}. Tl1e locations o��l�e
dewaterii�g vc�eXls aa-e shown on Coggins & Sons drawi�g XBS�2, Sl�eet 2 of 8, dated 8128/06.
G�-iffii� ��as also shov�nl well configtuatiorl and esizznated g�-ouz�.d water ele�ai:ions on a Cross
Sectio�� Well Sche�llatic dxawix�g. Cx����z� lxas iz�dicated an al��roxiillate sfiatic grolu�d watez-
elevai:ion of 8140, vcreXl scree��.s would Ue i��stalled froir� a��proxiinate elevat'ron $145 to elevatioia
� 8100, a�1d ground watez-would be lowered to ai1 ele�ation of 8107. Tl1e p�o�osed sl�.o�-iilg system
has bee�1 designed by Coggins & Sons, Inc.
We reviewed Griffins dewaieriilg plans a,r�d calculations a�id H�i' settlenzent calculations. H-�'
estii��ated ground s�ti:ieinerlt �o�- adjace��.t buildings Uased oii tlie ground wal;er Ueing lowe�ed 4D
feet az�d tlie deilse granular soil coz�ditxoz�s ezicouz�.tered izi their �oi7ngs. They also asswa�.ed ai1
avezage coln�ressioil potez�lial. of O.I% in their analysis. TI1E1T atlalysis estimates thai: a
settlement ��oteiltial of %z zncl� could occur. H-P also �tated tl1a�; their ailalysis is only for soil
coznpressibility and any i�.�.aterial re��.loved or "dredged" dui7ng dewateriiig lias Z�ot �aeen ✓'
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� Tom Kassinel .IfO.�'CHL�INCON,SDLTINGL'NGINEL'RS,INC
jNovez�.��ex17,200G Co�:sulting Geoteelxrrical .8rrgineers
f 7ob No.OG�130
,/” Page 2 of 2
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, cons�dez-ed. We are ii1 agreeznent witli their i1�ei:iiod of calculating settlement aa�d in gezieral
� agz-eex�nent with tlzeir settle�nent calculations.
II �izice diff�rent assuinptions can Ue anade for soil criteria thaf would influence dewatez�.��g and
settlenleilt calculations, we 11ave i��e following conce��ns for this site:
� T. Greatex cl.epths of dewateriil� i31ay occur in �ocaiized areas for vaults, grease pit,s,
, - _ ------------e�eva�ox pits,—and -t11e ��ei7naiiexit dewa�ez-�zig sys�em,whi�z co�d-i�:uerice a
j l�uzlding in the �zoximity a�t��ese st�-uctuxes. The locatioil ai�d elevatxozx of tlxese
i � st�-uctuxes should be indicated on l�laa�.s so that the influence oxi adjacent buildings
could be evaluated.
2. Localized sul��tu�'ace conditioils such as tlle layezs of si�ty sand could iilfluence
settleinent. The Iocatioz� aild de��th of tllese layers should be logged as tlze wells
are installed as�d as i��.e soils ase excavated.
� I� 3. SuUsoi� condxtzons Uezlea�li buildings could be di�'erent t��a�.the su�soil collditioils
encountered l�eneat��. tl�e site. This would influence t�ie soil criteria assuined
��, � l�eileatll Uuildings.
4. The dewa�:eru�g is based on estiinated groLUld water flow conditions and not on
puinp tests. The ground water coile of depression Uez�.eath adjacent buildings could
` be di££ezent tlian what is l�eing assuuned.
5. We�ls will be naturally developed an.d not gravel �acked with fltex xnediu�n so
soi�le loss of ground is a possibility.
i i 6. A inonitoring �xogzazn of Uuildings for settleinent arad sediznent measu�•en1e11ts of
;� ; �ufn�ed wafiex is �iazuzed.. What is tl�e altenlate �laz�. Uy the developinent team i�
; j • �noiutoring indicates loss of grouild or settleme�t of adjacent buildiilgs?
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7. Is a pezxx�az�.ent dewateF-ing system pXaiu�ed for the l�uiTding? Wi11 the long tezzli
' devs�aterix�g izafluence seitleinent beneatb ad3acezit buildings? I� so, wl�at is tlie
desig�.i layout, a�1d elevatioil o��le pzpes, suznps, etc.?
Z�we ca11 be o�fi.irtl�ez-seivice, �lease coi�tiact us.
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KOECHL��N CONSULTZATG��VGTNEERS, INC.
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Williaa��H. KOEC11I�111� P:E.���uriuu�m�s��u"�" ;�
President
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Reviewed By: Scoit B. Myezs, P.�.
Senior E1lginee�
(4 eopzes sent)
� cc: Jek�x�.Water Coi�sultai�ts