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Brent Bowman and Associates, Architects, P. A.
228 Poyntz Avenue
P.O. Box 1046
Manhattan, Kansas 66505
Attention: Mr. Tracy L. Reynolds, A.I.A., P.E.
Re: Geotechnical Engineering Report
Windsor Hotel Renovation
Garden City, Kansas
Terracon Project No. 01965043
Gentlemen:
Terracon Consultants, Inc. has completed a study of the foundation and bearing materials for the above-referenced project. As part of this study, a test pti was excavated ( with a backhoe) adjacent to the existing foundation, and a hand auger boreing was performed.
In this report, we describe the foundation and subsurface conditions encountered in the test pit/borehole, present the laboratory data obtained, and offer our opinions following our analysis of this information regarding the suitability of the foundations for support of the renovated structure.
SUBSURFACE EXPLORATION PROCEDURES
We attempted to perform test pits and hand auger borings at two locatins; one on the west side of the building and one on hte east side. Because of hte heavy reinforcement encountered in hte slab adjacent to the west side of the building, we were unable to complete this test pit. The test pit along the east side of the building extended to a depth of about 2.5 feet. A hand auger was then used to advance a boring to a depth of about 8.5 feet below sidewalk level. Representative samples were obtained from the boring y driving a tin-walled tube sampler and collecting auger cuttings at periodic depth intervals. Where granular soils were encountered, we also performed dynamic cone penetrometer tests. The dynamic cone penetrometer is an instrument that consists of a 10-pound dro phammer that falls a distance of 24 inches and is connected to a steel drive rod assembly that is tipped with a 1 1/8-inch diameter, conical point. Blows are recorded at 6-inch intervals. These blows give a general indication of the relative density of granular soils. The sampling depths and penetration distances are shown on the boring log.
LABORATORY TESTING
In the laboratory, the thin-walled tube sample was tested to determine its moisture content and dry density. The unconfined compressive strength of the tube sample was estimated witha calibrated hand penetrometer. The samples collected from the auger cuttings were tested to determine their moisture contents. The results of these laboratory tests are shown on the boring log adjacent to their respective sample locations.
As part of the testing program, an engineer examined the samples in the laboratory and, based on the material's texture and plasticity, described them according to the attached General Notes and classified them in accordance with the Unified Soil Classification System. The estimated group symbols for the Unified Soil Classification System are shown in the appropriate column on the boring log. A brief description of the Unified System is included in the appendex.
FOUNDATION AND SUBSURFACE CONDITIONS
Observations we made at the test pit, which was performed adjacent to the footing near the northeast corner of the building, indicated that the building is supported on a laid limestone foundation that extends about 12 inches beyond the face of the building. It appears that the wall on the east side of the building is about 18 inches thick. Therefor, the footing on the east side of the building is probably about 3.5 feet wide. We understand that the wood joists run north-south, making the east-west walls the primary load-bearing members.
The boring indicates that the footing bears on a nearly 1-foot thick layer of ver stiff, dark gray-brown to gray-brown, lean clay. Below the clay layer, we encounterd medium dense, silty find sand that extended to a depth of about 5.5 feet below sidewalk level. The silty find sand graded into brown, medium dense, fine to medium sand that extended to the bottom of the hand auger boring, a depth of about 8.5 feet below sidewalk level.
The subsurface conditions at the test pit/boring location are indicated on the boring log. The stratification boundaries shown on the boring log represent the approximate locations of changes in soil types; in situ, the transition between material types may be gradual.
WATER LEVEL INFORMATION
The boring was monitored for water while drilling and after completing the drilling operations. Water was not encountered in the boring at either of these times. Based on this information and the subsurface conditions encountered at the boring, it is our opinion that the groundwater table was located below the bottom of the boring at the time of our subsurface exploration. Fluctuations in groundwater levels are expected to occur due to seasonal variations in the amount of rainfall, runoff, and hte stage of the nearby Arkansas River.
BACKGROUND INFORMATION AND DISCUSSION
Our observations of the structure indicate that the south, west, and north sides of the building have a stucco finish, whereas the east side of the building is brick. With the eception of a few vertical cracks in the brick in the east building wall at the far south and north sides of the building, and a few vertical cracks in the stucco near the east end of the north side of the building, the perimeter walls of the structure were relatively crack-free. In our opinion, some of the cracking that we observed may be related to settlement, although the cracks at the south end of the east wall and some of the cracks at the north end of the east wall do not appear to be continuous down to the ground surface and, therefor, are probably not due to settlement.
Based on our observations, testing, and evaluations of the soils in the test pit, it is our opinion that the soils present at the base of the footings are suitable for a design bearing pressure of about 4,000 psf. Regarding the potential for additional settlement, if renovations to the structure do not result in additional wall loads, we do not expect significant, additional, logterm settlement.
GENERAL COMMENTS
The analyses and recommendations presented in this report are based upon the data obtained from the test pit/boreing performed at the indicated location and any other information discussed in this report. This report does not reflect any variations that may occur across the site.
We recommend that the geotechnical engineer be given the opportunity to review the plans and specifications so that comments can be made regarding the interpretation and implementation of this report.
This report has been prepared according to generally-accepted geotechnical engineering practices for the exclusive use of our client for specific application to the project discussed. No warranties, either express or implied, are intended or made.
We appreciate the opportunity to be of service to you on this project, and we are prepared to provide any appropriate construction monitoring and testing services. If you have any questions regarding this report, or if we may be of further service to you in other ways, please let us know.
Sincerely,
Terracon Consultants, INC.