The URL can be used to link to this page

Home My WebLink AboutBAUMER S-3430 (3) Mr. Rolf Strfckland Chief Sanitarian GAAB 3~JO C Street Anchorage, Alaska 99503 Lynn P. Wallace P.E. &839 Tampa Circle Anchorage, Alaska 99304 June 11, 1974 Dear Mr. Strickland; Re: S-3430 Baumer Subdivision The soils test holes for this subdivision were made to the depth o~ the harapau layer that supports the surficial soil deposits. This dept~ rangea ~rom 10-1/2 feet to 12-1/2 feet in the three test holes chat were excavated, as shown on the drawings and test logs which were submitted. The hardpan layer is a densly packed layer of non uniiormly gradea gravel sand and rockflour, genera~y classified as a GP soil. This hardpan layer generally extends downward fur au addztional ten to twenty feet in the subject subdivision, before bedrock is encountered. There is no evidence of a static water table on this hillside and all water seeps observed or reported, occur above the hardpan layer. Wells in the area are cased to bedrock and extend down approximately 75 to 80 ieet or greater ~rom the ground surface. The wells are supplied Zrom water seeping through the fractured bedrock from spurces on the mountains above. Utilizing this iniomation, I have determined that deeper excavations would not provide significantly different data and had the excavator stop after successfully penetrating the harapan layer. I therefq~ submit that the hardpan soil continues to a depth exceedin~ 17 feet and that no static water cable exist~ in the soil above this depth .%n the subject subdivision. cc Don Lucas 4839 Tampa Circle Anchorage, Alaska 99504 June 2, 1974 Greater Anchorage Area Borough Planning Department 3500 Tudor Road Anchorage, Alaska 99507 Attention: Mr. Wayne Mabry Subject-. Soils .Evaluation and Related Items - Baumer Subdivision, Resubdivision of TR 10, Donald C. Schroeder Subdivision, Addition #2 Dear Mr. Mabry: The following information concerning the soils conditions for the prop'gsed Baumer Subdivision located on the Eagle River Road in Eagle River, is submitted to satisfy the requirements of GAAB Ordinance No. 112-72A, Chapter 21; and Title .18, Environmental Conservation, 1'8 AAC 72.060 of the State of Alaska. Test Hole logs and project location maps follow the text. SITE LOCATION AND DESCRIPTION. The approximately 4.5 acre parcel .to be subdivided is located five miles east of the Glenn Highway on the Eagle River Road. The property is overgrown with Alders and Small Birch as a second growth after having been cleared for home- steading. 'The topography is generally sloping to the south becoming, s. te. eper near Hammond Road to the north of the property. ExISTING'WELLS AND SUBSURFACE DRAIN FIELDS. The location of existing ~ells on or near the parcel to be subdivided are shown on the project location map. Water has-been located in this area approximately 85' to 110' below the surface. Neighboring sub- divisions (not shown on map) have wells of sufficient capacity to supply domestic needs. The existance of reliable water sources in this geological area has been proven sufficiently to Borough~ Officials in the immediate past. Previous chemical and bacterio- logical testing of existing water sources has indicated that drinking water quality standards are satisfied, i FIELD EXPLORATION. On May 27, 1974, three(3) testholes were excavated on. site to depths of 12-1/2',12' and 10-1/2' respeCt-~ ively. The hole locations are shown on the location map. All holes were excavated by Hamann Construction Company of Eagle River, Alaska, using aCase Backhoe with a 1/2 CY bucket. Direct observations were made On soil strata and grab samples were taken both during and after excavation. Testh01e placement was made on each of the smaller three tracts to insure that soil conditions were as expected. There is more than sufficient room on the tracts to locate water and wastewater facilities. Creater Anchorage · Page 2 June 2, 1974 ea ,orough GEOLOGY. The Eagle River drainage area is located within the Chugach Mountains that border Cook Inlet. These mountains are a complex~ mixture of deformed and metamorphosed sedimentary and igneous rocks deposited during the late Paleozoic and Mesozoic Eras. Five major Pleistocine glacial advances along the consequent or subsequent lacustrine and alluvial deposits greatly influenced the present topography of the area.. The surficial geologic unit of the site appears to be part of the Eagle River cut as it worked through the late Pleistocene lateral moraine deposits. The till of this deposit is commonly sandy and stoney with cobbles common. Broken rock and Sand pre- dominate but silt and rock dust are ever present. Cobbles and rocks are rounded rather than angular. SUBSURFACE CONDITIONS. The ground cover over the site generally consists of a few inches of organic cover underlain with silty ~andy 'gravel with a trace of organics for another three feet. The ~urficial deposits of silty gravels or sandy silty gravels are i~ter-spersed with cobbles. The upper layer of material is of medium density and the lower level of harder density as evidenced by the effort of the backhoe during excavation. A consolidated layer was, encountered at three feet but was broken through at four and 1/2 feet. Below this layer was 5-1/2 feet of well graded .igravel. The soils in general can be classified as GW/GM by the Unified Soil Classification System. The hardpan appears to be a'GP soil. The gravelly soils contain about 60% by weight gravel or cobbles ~ith the remainder sand and/or silt. ? Grot{nd~a%er'was encountered °nly as a seeping flow just above the hardpan layer and not as a saturated level. Since the~water was flowing through the soil and not ponding, it is felt that the ground water level is much lower than the depth of the test holes. There was no visible evidence of ponded water,rather the. soil appeared to be well drained, but compact. CONCLUSION. Sufficient exploration has been accomplished on this small subdivision for the intended use with individual on-site water and sewer facilities. Each tract has sufficient acreage to allow for replacement soil absorption systems should the initial system fail. The soils are suitable with respect to foundation bearing capacity within the r~ge of conventionally applied bearing pressures' for Greater Anchorage A~a ~orough Page 3 June 2, 1974 residential continuous concrete footings. If other than convent- ional loads are anticipated, professional help may be required to design the foundation. The steep 'slopes must be considered in any foundation system. Please contact the undersigned if any expansion or clarification of these data is necessary. Re sp~.//~.~f ul ly /,"--L'~nn/ P.~%lace, P.E. %:' ' ::. LYNN p X.~77~1 / -,-% h /377~'A /J