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Mesa Pipeline
Slope Stability Evaluation
July 13, 2014
To: LINN Energy
Attention Torn Hoeglin
Project: Mesa Pipeline Alignment
RE: Slope Stability Evaluation of lower Buried Section
Tom,
As requested, Rock Solid Solutions Inc has conducted a review of the slope stability issues
associated with the proposed Mesa Pipeline Alignment from CR215 to the top of Old
Mountain. This evaluation consisted of review of geologic data, walking the alignment in
the field, photographing the alignment from various vantage points, reviewing the proposed
pipeline alignment and design as well as engineering experience and judgment in the area.
The geotechnical assumptions developed for this slope stability evaluation are based upon
our experience gained in working on the design, construction and maintenance of the
Garden Gulch Road Project; design, construction and maintenance of the Conn Creek Mtn
Road Rebuild Project, remedial storm water measures and monitoring of the Grantee Gulch
Road Project; isolated remedial measures for the Wheeler Gulch Road projects; and
remedial measures on the Logan Wash road. The geotechnical assumptions required for a
slope stability analyses are also based upon our knowledge of the site geology, our
experience with cuts and fills in the area for roads and pads, maintenance of site facilities in
the Piceance Basin and standard designs for public sector roads as well.
Because of the limited access to the alignment and the difficulty in getting subsurface data
along the proposed pipeline alignment, we have made a number of assumptions to develop
a generalized geotechnical section for evaluation of the slope stability at the lower end of
the pipeline alignment. The pipeline is proposed to be buried for about 110ft up the slope
just perpendicular to CR215. The shallow (6 -ft) deep trench required to bury the pipeline
will act more like a slot cut then a mass excavation. The slot cut geometry of the trench
excavation and the narrow nature of the excavation requirement would indicate that the
existing slope condition will not likely change much due to the excavation and or existence
of the proposed pipeline within the slope. Therefore, it is the opinion of Rock Solid
195 Lodgepole Circle, Parachute, CO 81635
Office: (970) 987-4247 Fax: (970) 712-5715
Mesa Pipeline Project
LINN Energy
Slope Stability Assessment Letter
7-13-14
Solutions that the stability of the slope adjacent to CR2I5 will not change significantly by
the construction and/or the existence of the proposed pipeline.
As a result, RSS does not believe the proposed Mesa Pipeline project will impact the
stability of the existing slope uphill of CR215. Surface water drainage and reclamation of
the pipeline cut should be an integral part of the construction process.
Limitations:
Rock Solid Solutions (RSS) has been requested to provide an assessment of the slope
stability associated with the pipeline alignment as designed by Construction Surveys Inc
(CSI). The design has been directed by LINN Energy of which RSS was a part of the
design team. Variability in the surface & subsurface conditions should be expected.
Variability in the design topography compared to the actual topography represents the
single most critical factor in the success of the pipeline alignment within the steep cliff
areas. Geotechnical data was limited to site visits and assessment based upon topographic
mapping, as well as from previous work and experience in the Piceance basin. Variability
of the work must be anticipated, therefore, it is imperative that the construction
management team consists of personnel familiar with these types of conditions and can be
proactive in modifying the design to provide cost effective solutions to topographic and
geotechnical issues that are unforeseen in the design. phase. RSS does not warrant the
assumptions provided in this report, but does warn the owners of the project that variability
will occur throughout the design, and construction of the project. The team selected to
construct and manage the work is critical to the success of the project.
RSS is confident that the Mesa Pipeline System to the top of Old Mountain can be
constructed in accordance with the means and methods outlined above and developed by a
competent conscientious contractor (or team of contractors). The team can and will be able
to construct the project such that the final pipeline system will meet or exceed the design
requirements set forth in the project drawings and proposed specifications.
Please call or email if you have any questions.
Respectfully,
IQ
Donald J. Berger, P.E.
Sr. Engineer
Rock Solid Solutions
.010.BILLLA 0h.
ROCK SOLED
SOLUTIONS
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