HomeMy WebLinkAboutObservation of Excavation 07.21.21lGrt#ffiffiffiiffü**
# 61n
An Employcr Owncd Compony
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 545-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
July 21,2021
Tom Fisher
1090 Fender Lane
Carbondale, Colorado 81623
tomfi sher(gìrocketmail. com
Project No. 19-7-268.01
Subject: Observation of Excavation, Proposed Residence, Homestead 1ó, Panorama
Ranches, 16 Panorama Drive, Garfield County, Colorado
Dear Tom:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on July 9, 15 and 21,2021to evaluate the soils exposed for foundation support. The findings of
our observations and recommendations for the foundation support are presented in this report.
The services were perfonned in aucotdance with oru'agleement for professional engineering
services to Tom Fisher dated April 15,2021.
The proposed residence will be a one-story wood-frame structure over a walkout basement level
with attached garage at the upper/main level.
At the time of our first and second visits to the site, the foundation excavation in the garage area
exposed some topsoil at the footing elevation. We recommended removing the topsoil to place
footings on the underlying natural fine-grained soils.
At the time of third visit to the site, the foundation excavation had been cut in multiple levels
from 0 to 7 feet below the adjacent ground surface. The soils exposed in the bottom of the
excavation consisted of sandy clay in most of the excavation and clayey sand and gravel in the
east side of the excavation. No free water was encountered in the excavation and the soils were
slightly moist to moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an allowable
soil bearing pressure of I ,500 psf should be adequate for support of the proposed residence. The
exposed soils tend to compress when wetted and there could be some post-construction
settlement of the foundation if the bearing soils become wet. Footings should be a minimum
width of 18 inches for continuous walls and 2 feet for columns. Loose disturbe.d soils in footing
areas should be removed and the bearing level extended down to the undisturbed natural soils.
Exterior footings should be provided with adequate soil cover above their bearing elevations for
frost protection. Continuous foundation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 12 feet. Foundation walls
acting as retaining structures should also be designed to resist a lateral earth pressure based on an
Tom Fisher
July 21,2021
Page2
equivalent fluid unit weight of at least 50 pcf for on-site soil as backfill. Â perimetcr foundation
drain should be provided to prevent temporary buildup of hydrostatic pressure behind the
basement walls and prevent wetting of the lower level. Loosc distrubcd soil, fill and topsoil
should be removed from below slab-on-grade areas. Slab subgrade can be reestablished with
structural fill. Structural fill placed within floor slab areas can consist of the on-site soils
compacted to at least 95% of standard Proctor density at a moisture content near optimum.
Backfill placed around the structure should be compacted and the surface pgaded to prevent
ponding within at leost 10 feet of the building. Landscapc that rcquires regular heavy irrigation,
such as sod, and sprinkler heads should not be located within 5 feet of the foundation
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
subsurface conditions within the loaded depth of foundation influence. This study is based on
thc assumption that soils bcncath the footings have equal or bettel support than those exposed.
The risk of foundation movement may be greater than indicated in this report because of possible
variations in the subsurface conditions. In order to reveal the nafure and extent of variations in
the subsurface conditions below the excavation, drilling would be required. It is possible the
data obtained by subsurface exploration could change the recommendations contained in this
letter. Our services do not include determining the presence, prevention or possibility of mold or
other biological contaminants (MOBC) developing in the fr¡ture. If the client is concemed about
MOBC, thcn n profcssional in this spccial ficld of practice should be consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kr¡rnar & ,,\ssoci¿rtes, Inc
James H. Parsons, P
Reviewed by:
Daniel E. Hardin, P.E.
JHP/kac
tL
Y.
s/e
ã86€0
Kumar & Associales, lnc.6 Project No. 19.7.268.01