HomeMy WebLinkAboutRe: soils/evaluation ~ `_
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ITCO ALLIED ENGINEERING C�.
AN ALLIANCE OF INSTANT TESTfNG COMPANY AND QLL[ED TEST D ILLING
Jobsite and Laboratory Testing, Geofechnrcal Services, Commercial, Residenfial and Municipal
7'I25 West 12fith Street, Suite#500 - Savage, MN 55378
Telephone: (952)890-736fi Fax: (952) 890-5883
March 11, 2014
Atlashomes Phone: 763-425-3333
14450 - 117�'Avenue North Fax: 763-390-0039
Dayton, Minnesofa 55369 mark@atlashomesmn.com
RE: 1565 Maple Place �
Orono, Hennepin County, Minnesota
As requested, a site visit was made on March 11, 2014 at 12:04 P.M, to evaluate and test soils for
the construction of a full basement single-famify residence. The proposed build area is located at
the middle of the 3 remaining lots within the tract. A subsurface geotechnical investigation#11036
conducted by A[fied Test Drilling Company indicates possible unsuitable soils within the
development, to an average depth of 6 '/2 to 8 feet, with ground water elevations varying from 14 to
20 feet.
At the time of the inspection, an area approximately 30 feet by 14 feet by 8 '/z feet deep had been
excavated within the SW section of the proposed build area. Removed materials consisted of
undocumented fill, containing {oamy soils, tree branches & root debris, wood, concrete, an isofated
car tire, and a 10" zone of organically stained clay (Horizon "B" soil). The base of the excavation
consisted of a wet, soft sandy clay, with a small isolated area of the Horizon "B" soil rerrzaining
adjacent to the east wall of the excaWation.
To assess the relative strength of the base soils, a 5/8�" inch diameter smooth probe was used at
random to penetrate the excavation interior. With full body weight applied, the probes indicated
medium/soft soils with probe penetration averaging 1 '/Z to 2 '/Z feet. Subgrade soil conditions were
further evaluated by a 1 5/8'h inch diameter fluted hand auger probe put down excavation. The
extracted cohesive soils were uniform in classification, and gained strength at depth.
The load bearing capacity of the soils were evaluated by a dynamic cone penetrometer test
conducted at the base of the excavation. The dynamic cone penetrometer (DCP), employs a eight
kilogram (17.6 pound) hammer to drive a 20 millimeter diameter canica! pair�t into the soil, with the
penetration recorded in millimeters per blow. From the DCP readings, a per blow, penetration
average was recorded and a N-value derived. This N-value is an empirical relationship we hav�
established to equate the dynamic cane data to the more familiar blows per foot (BPF) standard
penetration sail boring test.
f
Test#1 — Exca�ation Base (Near Mid-paint)
DCP Depth Per Blow Avq. / N-Vafue Estimated Load
824 MM (32.4°} 43.3 MM/N—7.3 2563 PSF
Based upon our observations and tests, it is recommended that all arganics and undocumented fill
be excavated from the building pad, and replaced with a granular engineered fill to proposed footing
elevation (estimated @ 4 to 5 feet} and below the building slab. This�II material should be
cansolidated with a vibratory compaction device at intervals of approximately 8 to 10 inches.
In our opinion, with the noted corrections, the observed and tested sub-grade soils are acceptable,
and would be expected to meet an assumed minimum bearing capacity requirement of 2000 PSF,
for the proposed construction. Our observafions and subsequent soil evaluation on this date is
limited in scope to soil conditions observed within the completed excavation, and to the depths
achieved by shallow probes and a dynamic cone penetrometer test.
Sincerely,
Itco AIlied Engineering Company Reviewed By:
� . Q��v�i:a 1J �y?Ca--O-�-`� �
�
Gary Standish Robert P, Sullentrop, P.E.
Senior lnspector Minnesata Reg. # 17823
CC: City of Orono Buiiding Inspections
701 - 1 1 #605-- 1 '/ / #610—'/4 1#304 I(1) DCP 1 #612—53