HomeMy WebLinkAbout1994-10-25 Excavation ReportA
A.MERIC.aS
ESGI\ERISG
TESTING, INC.
PROJECT:
RESIDENCE
3490 BIRCH LANE
ORONO, MINNESOTA
CONSULTANTS
• GEOTECHNICAL
• MATERIALS
• ENVIRONMLNTAL
OCT 2 5 1994
EXCAVATION OBSERVATIONS
AET JOB NO.: 94-2069
DATE: OCTOBER 24, 1994
REPORTED TO:
PISCHKE CONSTRUCTION
2148 65TH STREET EAST
INVER GROVE HEIGHTS, MN 55075
ATTN: WALLY PISCHKE
CC: CITY OF ORONO
ATTN: BRUCE VANG
INTRODUCTION
This report presents the results of the soil observations and testing we performed at the
referenced site. Our servi"s were conducted on a part-time basis. The scope of our work was
limited to the following:
• Observing some of the foundation excavation bottoms for the proposed residence.
• Drilling shallow hand auger borings in the bottoms of these excavations.
• Evaluating the suitability of the exposed soils to support the anticipated fill and
foundation building loadings.
• Providing recommendations for preparation of the foundation areas.
• Summarizing the results of the above in a written report.
Our work on this project was authorized by you on October 17, 1994.
*AN AFFiRMATI WE ACTION EMPI O.t R'
2101 (University Ave. W. • St. Paul, MN 55114 •612-659-9001 . Fax 612-659-1379
Duluth. Yankato. Rochester. Wausau
AET #94-2069 - Page 2
CONCLUSIONS
Based on the results of our observations and hand auger borings, it is our judgment the soils
finally exposed in the observed foundation excavation bottoms for the residence were suitable
for support of the anticipated fill and foundation loadings. Although the soils were competent,
it was our opinion they could easily become disturbed due to influx of groundwater into
excavations. We recommended precautions be taken to prepare the foundation areas, as
indicated in the following section.
"Riese conclusions are intended as a summary. Read the remainder of the report for specific
information.
RECONLyIENDATIONS
We recommended all fill and swamp deposits be removed from the foundation areas. The
excavation bottom should expose the naturally deposited alluvial sands. The excavation should
be deep enough to allow placement of at least a V thick layer of 3/4" or 11h" screened (clear)
rock or stone. The rock should be completely encapsulated in geotextile filter fabric to reduce
the potential for intrusion of the surrounding soils into the porous rock matrix.
We recommend 1:1 oversizing of the excavation bottom. That is, the excavation should be
widened, beyond the edges of the foundations, a distance equal to the depth of fill at that
location.
DESIGN INFORMATION
We understand the proposed residence will:
AET #94-2069 - Page 3
• Be 34' wide and 34' deep.
• Be a 1'fi-story structure with above -grade wood framing and no basement.
• Have a heated crawl space below the first floor.
• Have a wood -truss first floor planned at about 2'!z' above existing site grades.
• Have below grade cast in-place concrete foundation walls.
• Be supported on spread footing foundations designed to exert a unit soil bearing pressure
of no greater than 1,500 pounds per square foot (psf).
• Have normal tolerance to settlement.
• Be constructed according to applicable building code requirements.
Please note that deviations from the above design information could necessitate altering our
conclusions and recommendations. Contact us if the information stated is different from the
actual project design.
BACKGROUND I FOMIATION
To our knowledge, no test borings have been put down in the area of the proposed building.
Because of this, we cannot comment on the soil conditions at depth. Our judgments reported
herein are based only on those soils which were observed at the surface, and those probed by
our shallow hand auger borings. In order to further explore conditions at depth, deeper
penetration test borings should be performed.
EXCAVATION OBSERVATIONS
We observed some of the foundation excavations for the proposed residence on October 10,
1994. We were not present at the site on a full -die basis. Our services consisted of a single
visit to the site at your request. Besides observing the soils exposed. we drilled shallow hand
AET 1194-2059 - Page 4
auger borings in the bottom of the excavation. The soils encountered were classified in general
accordance with ASTM:D2488 and estimates were made of their strength properties.
The soils exposed in the bottom of the observed excavations, and those retrieved by the hand
auger borings, were classified as sand with silt (SP -SM), silty sand (SM) and clayey sand (SC).
We judged these soils to be naturally deposited alluvial soils in a loose condition or with a soft
to -medium consistency. We judged these soils capable of supporting the anticipated fill and
1,500 psf foundation loads.
Standing water was present in the bottom of a previously excavated foundation area, in the
eastern portion of the residence. Water was also observed entering the newly excavated
foundation areas. The water level appeared similar to that of adjacent Lake Minnetonka.
The bottoms of the observed excavations varied from about 4' below original surface grade in
the northeastern corner of the building to about 5',A.' below the surface near the northwest cotter
of the building. The appended sketch illustrates the extent of the excavation at the time of our
observations. This data was obtained using staking and elevation information provided in the
field.
Since the observed excavations terminated below foundation grades, we recommend 1:1
oversizing of the excavation bottom. That is, the excavation should be widened, beyond the
edges of the foundations, a distance equal to the depth of fill at that loc.—ion.
STANDARD OF CARE
Our services for this project have been conducted to those standards considered normal for
services of this type at this time •ind location. Other than this, no warranty, either express or
implied, is intended.
AET #94-2069 - Page 5
The following sheets are attached and constitute an integral part of this report:
Earthwork Information Sketch
Earthwork Quality Control Information
To protect the client, the public and American Engineering Testing, Inc., this report (and all
supporting information) is provided for the addressee's own use. No representations -e made
to parties other than the addressee.
Report Prepared By:
jejf�ey'P. PE
Sr. Geotechnical Engineer
MN Reg. #20742
Report Reviewed By:
Michael P. McCarthy, PE
Principal Engineer