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Home My WebLink AboutCorrespondence Miscellaneous 7/21/2006 , .' . l- }~;l Information ~..,. .To Build On Engineering. Consulting . Testing . " July 21, 2006 Mr. Mark Vukanovich Suntrust Land Company LLC 780 NW York Drive, Suite 204 Bend, Oregon 97701 Re: Earthwork Summary Letter for Individual Building Lots Mountaingate Subdivision - Phase 4 Lots 1 through 129 Springfield, Oregon 97478 PSI Report No. 722-65013-103 Dear Mr. Vukanovich: PSI is pleased to submit our earthwork summary letter and geotechnical requirements for individual building lots for the Mountaingate Subdivision Phase 4 - Lots 1 through 129 in Springfield, Oregon. PSI has been providing observations during construction of the building pads from February 9, 2006 to present. The earthwork was performed by ,Qai<rlc!ge _S'ind_.a[ld~ravel under the ,direction of the,geQeral contractor Eugene Sand and Gravel. Observations during our site visits were documented in .our daily field reports which were typed and contained a site plan showing the areas the contractor was working on'those days. Please reference those reports 722-65013-1 through 722- 65013- 102. Copies of those reports were also provided to Eugene Sand and Gravel, Oakridge Sand and Gravel, City of Springfield, and The Favreau Group. Based on our observations during the time frame mentioned above, the earthwork was performed in general accordance with the project geotechnical report prepared by Boire and Associates, Inc. dated April 5, 2004, City of Springfield requirements, and applicable provisions of the current International Building Code. The secondary purpose of this letter is to outline geotechnical engineering investigations that should be completed for individual lots 1 through 129 prior to residential ,construction. To be consistent with criteria established during construction for Phases 1, 2, and 3 by Boire Associates, Inc, and KA Engineering in letters dated February 10, , 2005 and March 28, 2006, respectively, we are recommending Level I and Level II geotechnical investigations be performed on Lots 1 through 129 as follows: Level 1 Geotechnical Investigation To be consistent with the previously submitted reports, we recommend a level 1 geotechnical investigation be performed for the residential building lots where the subsurface conditions are known to consist of competent soil or rock and have been observed by PSI during grading operations performed by the earthwork contractor. Lots in the Mountaingate Phase 4 area that fall into this category are 7 through 23, 29. through 34, 40 through 61, and 74 through 101.' Data Received: T 2.1-ob Pla~ner." '/ Df';) p~ ',' , , \M.C&nu.kCS CO I v-es r Professional Service Industries, Inc. . 1040A Shelley 81.. Springfield, OR 97477. Phone 541/746.9649. Fax 541/746-7163 - · Earthwork summ!Letter for Individual Lots Mountain Gate Subdivision- Phase 4 Lots 1 through 129 Springfield, Oregon 722-65013 'Page 2 In general, the lots in Level 1 should not require extensive grading operations to construct the single family residences. Accordingly, a lot specific geotechnical investigation is not expected for foundation design prior.to construction of the Level 1 residential buildings. We recommend that a geotechnical engineer or representative observe these lots during excavation to verify that the above listed conditions have been satisfied and the subgrade conditions are suitable for construction. As a minimum the geotechnical engineer should provide: 1. Verify that site work does not adversely impact adjacent lots, utilities, and street improvements. 2. An examination of all foundation excavations during construction to verify design criteria assumptions and to provide recommendations, if necessary. 3. Note any special, unexpected, or latent conditions that would require a level" investigation. Please note that.at the time olthis letter ,some of,the Levei 1 Jots have been proofrolled at finished subgrade elevation with a.loaded tandem axle dump truck to assist us in determining the stability of the soils placed on the lots. Please reference the attached site plan for lots tha't have been proofrolled. Lots that have not yet been proofrolled include Lots 7 through 9, 15 through 23, 34, 40 through 54, 74 through 83, and 91. Lots that were proofrolled and observed to be deflecting and wheel tracking under the weight of the loaded dump truck include Lots 29, 30, 55 through 57, 59, 88 through 90, and 95. These lots should be re-proofrolled prior to residential construction. As mentioned in our previously submitted reports, Lots 97 through 99 have been capped with material that is potentially expansive based on laboratory tests. This material should be removed prior to residential construction. level 2 Geotechnical Investigation We suggest a Level" Investigation be completed on all other remaining lots in Phase 4 where no grading operations have yet been performed and the lots are currently in their natural state. Some of these lots may be steep, the subsurface conditions unknown, and structural fills and/or retaining walls may be needed. We recommend lots 1 through 6, 24 through 28, 35 through 39, 62 through 73, and 102 through 129 be included within 'the Level " category. In general, the lots in Level 1 may require extensive earthwork or grading operations to construct the single family residences. For lots within the Level II categorY, we recommend a site-specific geotechnical investigation be completed prior to home site development. Within these areas, particular attention should be given to: unstable ground, 'soft/wet soil conditions, expansive soils, drainage, cutslfills, and retaining walls. The following items are suggested as minimum requirements for the geotechnical investigation reports. · Earthwork summ! Letter for Individual Lots Mountain Gate Subdivision - Phase 4 Lots 1 through 129 Springfield, Oregon 722-65013 Page 3 1. Subsurface explorations using either exploratory test pits and/or soil borings to determine foundation conditions. 2. Laboratory analysis of the soils to include at least moisture content and dry density, gradation, and Atterberg Limits tests. Testing may also include Expansion Index if the soil is potentially expansive based on visual analysis. 3. A written report prepared by a qualified geotechnical engineer that summarizes the site conditions, presents the laboratory test results, and addresses the recommendations for cutslfills, foundations, drainage, retaining walls, and other items that may be necessary to the development of the proposed residence. Similar to Level I lots, we recommend that a geotechnical engineer or representative observe these lots during excavation to verify that the above listed conditions have been satisfied and the subgrade conditions are suitable for construction. As a minimum the geotechnical engineer should provide: 1. Verify that site work does not adversely impact adjacent lots, utilities, and street improvements. 2. An examination of all foundation excavations during construction to verify design criteria assumptions and to provide recommendations, if necessary. 3. Note any special, unexpected, or latent conditions that would require a level II investigation. It is recommended that PSI be retained to examine and identify soil exposures created during project excavations. to verify that soil conditions are as anticipated. We further recommend. that structural fills, if any, be continuously observed and tested by our representative to evaluate the thoroughness and uniformity of compaction. Samples of fill materials should be submitted to our laboratory for evaluation prior to placement of fills on site. This report is for the exclusive use of the addressee and their representative to design the proposed structure described herein and to prepare construction documents. The data, analyses, and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. In the absence of our written approval, we make no representation and assume no responsibility to other parties regarding this report. The recommendations contained in this report are based on the available subsurface information obtained by PSI, and design details furnishea for the proposed project. If there are any revisions to the plans for this project, or if deviations from the subsurface conditions noted in this report are encountered during construction, PSI should be notified immediately to determine if changes in the foundation recommendations are required. If PSI is not retained to perform these functions, PSI will not be responsible for the impact of those conditions on the project. . . . . . ..-= ,,- -.-. -'--- .'.-- .. ~~"'-"""""'-'..""'-' -_. . .~.-:- ~~~- _:~-.~: --eo. Earthwork Summary Letter for Individual Lots Mountain Gate Subdivisionc.'Phase 4 Lots 1 through-129 Springfield, Oregon 722-65013 . Page 4 Services performed by the geotechnical engineer for this project have been conducted with that level of care and skill ordinarily exercised by members of the profession currently practicing in this area. No warranty, expressed or implied, is made. Respectfully Submitted, - Professional Service Industries, Inc. ~~,aap Raymond V. Aliperti Project Manager Richard W. 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