HomeMy WebLinkAboutObservation of Excavation 12.15.2022K+AKumar & Assockdes, hic® .
Geotechnical and Materials Engineers 5020 County Road 154
and Environmental Scientists Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
An Employee OwrWd Compeny www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
December 15, 2022
Modfin Design + Build LLP
Attn: Keith Wittenberg
243 Elk Ridge Drive
Glenwood Springs, Colorado 81601
shag sWi( yahoo.com
Project No. 21-7-81 LA
Subject: Observation of Excavation, Proposed Residence, Lot 61, Spring Ridge Reserve,
789 Hidden Valley Drive, Garfield County, Colorado
Dear Keith:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on December 15, 2022 to evaluate the soils exposed for foundation support. The
findings of our observations and recommendations for the foundation design are presented in this
report. These services were provided in accordance with our agreement for geotechnical
engineering services to Modfin Design + Build LLP dated December 12, 2022. We previously
conducted a subsoil study for design of foundations at the site and presented our findings in a
report dated November 22, 2021, Project No. 21-7-811.
The proposed residence will be a split level one- and two-story residence with partial walkout
basement level and attached garage. The ground floors will be slab -on -grade. The residence has
been designed to be supported on spread footings sized for an allowable bearing pressure of
4,000 psf.
At the time of our visit to the site, the foundation excavation had been cut in multiple levels from
1 to 10 feet below the adjacent ground surface. The bearing material exposed in the bottom of
the excavation consisted of siltstone bedrock. A limited depth (6 inches or less) of soil and well
broken bedrock had been placed to establish bearing level in over -excavated areas of the
foundation. There was snow cover on the site and the foundation excavation was protected with
concrete blankets. No free water was encountered in the excavation and the soils and bedrock
were slightly moist.
The bedrock conditions exposed in the excavation are consistent with those previously
encountered on the site and suitable for support of spread footings designed for the
recommended allowable bearing pressure of 4,000 psf. Loose disturbed material should be
removed in the footing areas to expose the undisturbed siltstone bedrock. The bearing materials
should be protected from frost and concrete should not be placed on frozen soils. Other
recommendations presented in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous, limited, subsurface exploration at the site.
Modfin Design + Build LLP
December 15, 2022
Page 2
Variations in the subsurface conditions below the excavation could increase the risk of
foundation movement. We should be advised of any variations encountered in the excavation
conditions for possible changes to 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 future. If the client is concerned about MOBC, then a
professional'in this special field of practice should be consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Associates,
vo.; •may +�. P�
James H. Parson Pr. 58663
Rev. by: SLP
JHP/kac
Kumar & Associates, Inc. ' Project No. 21-7-811.A