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Home My WebLink AboutGEO General M GEOTECHNICAL TESTING LABORATORY TO BE KEPT IN TI-i C LARRY BLACK PARCEL FILE 2001 HOLIDAY CIRCLE OLYMPIA,WA 98501 Re: Parcel#22026090084 Gentlemen: On Dec. 6, 1996, Harold Parks, Engineering Geologist, of Geotechnical Testing Lab, visited the above mentioned site for the purpose of investigating the slope and soils for potential construction on the site. Samples of the soil were collected in moisture-proof containers and I returned to our lab for testing. The results of our observations and analyses are as follows: SITE & SOIL CONDITIONS: i The acreage is located on the south end of Hartstene Island in Mason County, Washington. (See Vicinity Map) The site is accessed by a road panning north/south and located on the eastern side of the propem•. A very gentle draw runs east and west at the southern end of the two one-acre sites. This seasonal drainage Swale runs west and discharges into Peale Passage at the southern portion of the subject area. The only steep slopes are on the waterfront side of the site. Soil on the site is snapped by USDA Soil Conservation Service as a Hoodsport Gravelly Sandy Loam. This soil has a rapid internal drainage with slow runoff characteristics. Large trees are located on the site with low shrubs indigenous to the northwest. HILLSIDE FOUNDATIONS(DAYLIGHT DIMENSION) Structures built on sloping sites otTer a number of potential problems. Fig. i illustrates a basic consideration for what is called the "daylight"dimension, which is the horizontal distance from the bottom of the footing to the adjacent ground surface. Many building codes require a minimum distance for this dimension in order to assure some safety against the pushing out of i the footing in the downslope direction. Logically,the limit for this distance depends on the type of soil and the angle of the slope of the ground surface. For low slope angles, a reasonable daylight dimension is assured simply because of the usual requirements for the minimum depth of the bottom of the footing below the surface in a vertical direction. As the slope increases,the daylight dimension is less assured and should be limited to some minimum distance. A common problem with hillside construction is that shown in Fig. 2,where recontouring of the construction site results in a portion of the building being placed on some significant depth of fill. if possible, all of the footings should be carried down to a depth below the fill. If structural fill is used and placed with reasonable compaction, it may be possible to rest the footings in the fill, provided that this is done only with inspection and supervision by a qualified soils consultant. 10011 Blomberg Street SW.Olympia,WA 98512 Phone W:(360)754-4612 Fax 9:(360)754-4848 GEOTECHMCAL PA RC T f I TESTING LABORATORY �'I� ' A close examination of the subject lots showed no signs of cracking and slumping. It is our opinion that the slopes are sound,but we recommend that any building built on a lot observe the (DAYLIGHT)principle mentioned in this report and meet a setback of 35 & from the crest. Low shrubbery and vegetation should be encouraged to grow on the slope to mitigate erosion. The owner of a particular lot should retain the services of an engineering geologist to insure the stability of the home and the slope prior to building. ISUMMARY& RECOMMENDATIONS: All material excavated and dumped on the site for building pads and roads must have adequate ' subgrade preparation at the fill location and proper fencing and runoff controls. All spoils soil must be compacted to 90%MDD as per ASTM D 1557 and protected from erosion. All ditching ' and drains must be installed with suitable discharge facilities. in the footing area, the foundations for any homes must be placed in the firm native soil or certified compacted fill. All footing drains must be placed so that the invert is below the bottom of the footing. No roof drain shall be connected to the footing drain. The conclusions and recommendations in this report are based on our interpretation of site conditions as they presently exist, anticipated future construction activities, and the expectation that our exploratory efforts adequately define the subsurface conditions throughout the site. Our investigation is based on the materials observed and soils analyses performed, and we believe them to be representative of the entire foundational area. In the event that the scope or location of the project should change, or subsurface conditions different from those encountered during our study be observed or suspected, we should be advised. At that time,a review of the changed conditions will be made and alternative or remedial recommendations given as requested. If you have any questions concerning the test results,the procedures used, or if we can be of any ' further assistance please call on us at(360)754-4612. Respectfully Submitted, ' GEOTECIINICAL TE&FING LABORATORY Harold Parks, Engineering Geologist 10011 Blomberg Street sw.Olympia,WA 98512 Phone#:(360)754-4612 Fax#:(360)7544848 GEOTECHNICAL TESTING LABORATORY • anyugt►r � FIGURE 1 Critical expusurc condl(ion for a I�IUsids fuu(ing. . �" FIGURE 2 Problems of foundations on graded hillside al(es. 10011 Blomberg street SW,Olympia,WA 98512 Phone#:(206)7544612 Fax#:(206)7544948 • GEOTECHNICAL TESTING LABQRATORY TJ eF-- KEI":)T IN PA,Rc RIS SITE PLAN 51.00 Full !� EXISINVC �, o•unirr' f a � j rM N- LOT IAMU A 1.00eACM alp f, N N asm"•r Poll i � fr tf 1><Et • w PROPOSED f LMACM 1 wimpsmw :a FOUNT I l� s142 MY .>r se,d..• � tJao1 r>Err i Ilool l Blomberg Street SW,Olympia,WA98312 Phone 8:(206)754-4612 Fox N:(206)754-4848