HomeMy WebLinkAbout03.03 Binder 2 - Appendix D•
•
March 14, 2000
Spring Valley Development, Inc.
411 East Main Street, Suite 205
Aspen, CO 81611
Attention: Mr. Bill Peacher
President - Development
Subject: Geologic and Geotechnical Consultation
Two Water Tank Sites
Spring Valley Ranch, P.U.D.
Garfield County, Colorado
Job No. GS -2972
Gentlemen:
We are in the process of performing a geologic evaluation and geotechnical
investigation for the two water tank sites at Spring Valley Ranch P.U.Q. under this
job number. Due to the presence of snow cover and need for access drives to be
pioneered to the sites, we will be unable to perform our field investigation until after
spring snow melt and construction of access drives. We have prepared this letter
presenting preliminary opinions regarding the feasibility of constructing the planned
water tanks at the proposed sites from a geologic and geotechnical viewpoint. This
letter is based on a site visit, evaluation of aerial photographs and our experience.
The following paragraphs provide a description of the tank sites and our opinion of
feasibility.
The first tank site is located on the floor and sides of Landis Creek at the
location shown on the attached Figure 1. The Landis Creek Tank Site is at the base
of and on the lower parts of steep slopes mapped as Potentially Unstable Slopes
(map unit PUS1). Based on our observations at the site and evaluation of aerial
photographs, we believe the slopes may be unstable. We suggest moving the Landis
Creek Tank Site several hundred feet up stream to where the existing slopes appear
stable. We believe the tank can be built in the suggested area shown on Figure 1.
Our geologic evaluation and geotechnical investigation will assess slope stability
and provide design level geotechnical recommendations. We anticipate that slope
retainage will likely be needed.
CTL/THOMPSON, INC.
CONSULTING ENGINEERS
234 CENTER DRIVE • GLENWOOD SPRINGS. COLORADO 81501 • (970) 945-2809
The second tank site is located at higher elevations on the top of a low ridge
to the east of Lot R-60 at the location shown on the attached Figure 2. The upper tank
site is not located in an area of geologic hazards. Vegetation at the site consists of
dense conifer and aspen forestation. We believe the site is underlain by bedrock of
the Pennsylvanian aged Maroon Formation at comparatively shallow depths. We
believe the water tank can be built at the proposed site, however, shallow bedrock
may make excavation difficult and the need for blasting should be anticipated. Our
geotechnical investigation will identify subsurface conditions and provide design
level geotechnical recommendations.
We appreciate the opportunity to work with you on this project. If you have
questions, please call.
Very truly yours,
CTLITHOMPSON, INC
Wilson L. "Liv" Bowden , C.P.G.
Engineering Geologist ..•3 _/ 7UDU
Reviewed by:
John Olecfiling, P.E.
Br
LB:JM:cd
ch Manager
(6 copies sent)
SPRING VALLEY DEVELOPMENT, INC.
TWO WATER TANK SITES
SPRING VALLEY RANCH P.U.D.
JOB NO. GS -2972
2
JOB NO. GS -2972
FIG. 1
JOB NO. GS -2972
F . 2
December 18, 2000
Spring Valley Development, Inc.
411 East Main Street, Suite 205
Aspen, CO 81611
Attention: Mr. Bill Peacher
President - Development
Subject: Geologic and Geotechnical Consultation
Two Water Tank Sites
Spring Valley Ranch, P.U.D.
Garfield County, Colorado
Job No. GS -2972
Gentlemen:
We have prepared this letter to present our opinions regarding construction
of the planned "upper" and "lower" water storage tanks. We previously published a
letter, dated March 14, 2000 under this job number which discussed the tank sites.
This letter is based on our site visits, field reconnaissance, evaluation of aerial
photographs and our experience. The following paragraphs provide descriptions of
the tank sites and our opinion regarding of tank construction at the sites.
The "lower" tank site is located on the floor and sides of Landis Creek. The
tank will be a 1.0 MG storage tank built upon an approximately 10 feet thick mat of
structural fill. A retained excavation into the existing hillside, laid back at a slope of
1/2 to 1 (horizontal to vertical) is planned to create the fill bench for the tank. The fill
bench will be a mechanically stabilize earth (MSE) structure towards Landis Creek.
We believe that the planned tank construction can be accomplished without
significantly reducing the existing hillside stability. It appears retainage of the
excavation via soil nails will be most appropriate to maintain global stability and
retain the excavation face. Future geotechnical studies will assess slope stability and
provide design level geotechnical recommendations.
The "upper" tank site is located at higher elevation on the top of a low ridge
to the east of Lot R-60. The upper tank site is not located in an area of geologic
hazards. Vegetation at the site consists of dense conifer and aspen forestation. The
• site is underlain by bedrock of the Pennsylvanian aged Maroon Formation at
CTL-/THOMPSON, INC.
CONSULTING ENGINEERS
2',4 CENTER DRIVE • GLENWOOD SPRINGS, COLORADO 816C1 • <970) 945.2809
comparatively shallow depths. The water tank can be built at this site with minimal
required earthwork. Shallow bedrock may make excavation difficult and blasting
should be anticipated. Future geotechnical studies will identify subsurface
conditions and provide design level geotechnical recommendations.
We appreciate the opportunity to work with you on this project. If you have
questions, please call.
Very truly yo s
CTL/TH0
J
N,
n
Bran
JM•.�
d
9
Manager f �"
copies sent)
SPRING VALLEY DEVELOPMENT, INC.
TWO WATER TANK SITES
SPRING VALLEY RANCH P.U.D.
JOB NO. GS --2972
2
•
•
•