HomeMy WebLinkAbout1.15 Geologic and Soils Report1517 Blake avenue, suite 101
Glenwood Springs, CO 81601
970-945-8676 phone
970-945-2555 fax
www.hceng.com
An Employee-Owned Company
GEOLOGIC AND SOILS REPORT
The proposed small contractor’s yard within Parcel 1 of Rifle Village South, according to
geological hazard maps provided by Garfield County, is not a slope or soil hazard nor is the
surficial geology a geological hazard. These maps are provides within Tab 9 of the application.
The attached soils classification map from the United States Department of Agriculture, Soil
Conservation Service’s “Soil Survey of Rifle Area, Colorado, Parts of Garfield and Mesa
Counties” shows the entire site be Arvada –Torrifluvents-Heldt. This soil is not ideal for
community development due to high shrink-swell potential and should not be built upon with
structures. However, since a proposed gravel area and some leveled areas for storage is all that
is proposed, there should be no concerns with the proposed usage.
The applicant has noticed that the soils are prone to erosion and the land around the yard has a
number of sinkholes. The manager of the contractor yard will be responsible to monitor the 1.26
acres of land to watch for any subsidence in the ground. The site should be examined quarterly
at minimum as well as after any major storm runoff events. The applicant has agreed to fix the
access paths and storage areas when subsidence is noted and fill with imported structural
material until the areas have stabilized and storage materials can be returned to the location.
The retaining wall that currently existing and which will be modified on the site is a gravity
block system. These systems are suitable for scenarios which we have on this site. This location
has the top of wall at a high point so there isn’t a large loading on the wall from a uphill slope.
The grading at the top of the wall also allows drainage to drain to the west away from the wall
and the grading at the bottom of the wall flow to the east away from the wall. This type of wall
does not require geogrid for this scenario of a 1-4’ tall wall with minimal loading.
The drainage to the south of the proposed contractor’s yard is sheet flow towards the
north/northwest. The deep draws on the contractor’s yard begin abruptly within the limits of the
contractor yard and to not have a large drainage basin associated with them. The only runoff
appears to the portions of this draw on the proposed contractor’s yard is approximately 0.33
acres of land between the driveway and the draw.
This land is difficult to establish revegetation. The applicant is proposing to place a dry seed mix
as shown on the grading plan on the disturbed ground not covered in retaining wall and gravel.
If the revegetation has not taken hold after a field inspection 12 months following the seeded,
drill seeding and irrigation may have to be considered. The applicant is willing to follow the
recommendations of the County Inspector.
Daniel Dennison
High County Engineering
Land Surveying Civil Engineering