HomeMy WebLinkAboutObservation of Excavation 06.22.2022
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
June 22, 2022
Tyler Miles
16425 County Road 309
Parachute, Colorado 81635
tymiles2010@gmail.com
Project No. 22-7-427
Subject: Observation of Excavation, Proposed Residence, 188 Eagle Ridge Drive,
Battlement Mesa, Garfield County, Colorado
Dear Tyler:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on June 15, 2022 to 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 performed in accordance with our agreement for professional engineering services
to you dated June 14, 2022.
The proposed residence will be a one and two story wood frame structure with a slab-on-grade
ground floor. Foundations were designed for a maximum soil bearing pressure of 2,000 psf.
At the time of our visit to the site, the foundation excavation had been cut in one level from ½ to
4 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of whitish, sandy clayey silt to clayey silty sand with gravel. Results of percent finer
than sand size gradation analysis and moisture density testing indicate the soils are potentially
settlement prone under conditions of loading and wetting. 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 1,200 psf are recommended 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 20 inches for continuous walls and 2 feet for columns. Loose and disturbed 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 (if any) should be designed to resist a lateral earth
pressure based on an equivalent fluid unit weight of at least 50 pcf for on-site soil as backfill. A
perimeter foundation drain should not be installed for the proposed slab on grade main floor.
Structural fill placed within floor slab areas can consist of the on-site soils compacted to at least
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No. 22-7-427
SAMPLE LOCATION NATURAL MOISTURE CONTENT
NATURAL DRY DENSITY
GRADATION
PERCENT
PASSING NO. 200 SIEVE
ATTERBERG LIMITS UNCONFINED COMPRESSIVE STRENGTH SOIL TYPE BUILDING AREA
DEPTH GRAVEL SAND LIQUID
LIMIT
PLASTIC
INDEX (%) (%)
(ft) (%) (pcf) (%) (%) (psf)
Southwest
Corner
Footing
grade 15.4 75 79 Sandy Clayey Silt
Northeast
Corner
Footing
grade 11.1 77 45 Clayey Silty Sand