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HomeMy WebLinkAboutKARVIEW Plat# 77-74 S-3831 DEPARTMENT OF ttEALTH AND ENVIRONMENTAL PROTECTION PLATTING OR PLANNING AND ZONING CASE REVIEW PETITION FOR Date Received Comment to COMMENTS: Rezoning · Special Exception VACATION t RESUBDIVIS~0N ENVIRONMENTAL SANITAg, IO~: for meeting of of Cases PUBLIC WATER NOT AVAILABLE PUBLIC SEWER NOT AVA~tI~ABLE TO SERVICE 'ENVIRONMENTAL ENGINEERING: DE,-MRTMENT OF ENVIRONMENTAL QUALITY PLATTING OR PLANNING & ZOHING CASE REVIEW CASE NO. ~-.~3/ T ITL E: ~fnm~//~ ~ Date Case Received By Suspense Date Comments to Planning Department For Planning & Zoning Commission Meeting Date ROUTING Environmental Engineering Air Pollution Noise Environmental Sanitation COMMENTS: 127 West Firewood Lane, Anchorage, Naska 99503 , (907) 2.79-7011 Engineers, Geologists and Geoptwsicists JAY M, ENGLAND Pro[esslonnl Engineer Associate*in-Charge DUANE L. MILLER Professional Engineer September 23, 197~~''°fE''¢n*e' 0050,005.08 Unwin & Scheben Consulting Engineers 103 E. 26th Ave. Anchorage, Alaska 99503 Attention: Go.. o. on Unwin Gentlemen. This letter presents our evaluation of the soil conditions for waste water disposal on Lots 1 and 2, Karview Subdivision, Anchorage, Alaska. As shown on your preliminary plat dated June 6, 1975, the lots are located on the east side of Hide- away Drive and are each about 1.1 acres in size. One test pit was excavated on each lot at the locations you designated using o~.cknoe equioment. The purpose of -the -best oits were to evaluate the subsurface soil and ground water conditions and to determine the absorotion area requirements :o_. o. msposa.,, of seDt~_c tank ef .... nen~. The pi~s were dug under -the direction of our field engineer who logged the materials encounqered and obtained grab samples representative of sign- _,.¢.zc~n~ soil layers, mhe Logs of the Test Pits are presented on the a~tached plate which includes a description of the pi~ locations. The soils were c!assz:c].ed in accordance ''' the Unified Soil Classification System. .... ' ' ' 1 '-h -"~urface organic mat consist of silty sands ~h~ Soils (SPI) and sands (S}) with an occasional interbedded lapr of .. ~.' p"~ - 1, a small qua~.tity of ~J.l.t and ~ravel. In Teoc .~z~ A on Lot ground water seepage was .encountered in a. two-foot-thick ].ayer ~..~ .... ~ ,- . _ . -c..e surface No other free o'~] .... a~. aoou'e fi{~e~feet below ground water was encountered to the deeths explored. We recommend that the seepage pits or trenches for the effluent from 'the septic tanks extend to, and bottom in the gravelly sand layer, which was encountered in Test Pit ~ about eleven and one- half feet below the surface. This material is classified as SP material and is relatively permeab].e. Absoretion trenches bottomed in ',;his material will require 150 square fee~c of absorption area per bedroom in accordance with Greater Anchorage Area Borough (GAAB) design requirements. Unwin & Scheben September 23, 1975 Page Two Test Pit A on Lot 1 terminated at eleven feet because of slough- ing and water inflow from surface runoff and shallow seepage and was not of sufficient depth to reach the sand layer encountered in Pi'~ Bo If the (SP) material is not present on Lot 1 at about the same depth as on Lot 2, the ~osorption trenches on Lot I should be designed for Silty Sand (Sb!) type soils which require 250 square feet of absorption area per bedroom (GAAB requirements). The absorption trenches should be sealed so that surface runoff and shallow seepage will not infiltrate into the system· This can be accomplished by backfilling the surface of each trench and any zone of shallow seepage with relatively impermeable silty · _.~_. ' ' ~ 'l ' ~ material Alternative].y~ a. suodr~azn .can oe ns~=,.ted-~o s.l.o~e fmom.~ahe.system to intercep'~-~and conduct ground water away from t~:~e absorption fie]id.' ~ The installation of the sewage disposal systems should be in accordance with all GAAB requirements for these facilities. Very truly yours, T{ARDING- LAWSON ASSOCIATES Jay M England Associate Engineer A-[:tachment: Logs of Test Pits JME/khe :j LOG OF ---om A .~ ~: ..... P Z T Test Pit A located on Lot .1., 25' south of the North Property line and 95~ East ©f centeriine ef Hideaway Drive. Test Pit 13 located on iboh 2, 30' north of the south property line and idg' east of center!ine of Hideaway Drive. 10- Equipment John Deere Backhoe Elevc¢{on 984 -~ * Date g-18-75 ,i ,i. 'k . ~[3RO?,'N SILTY SA?~I) (SPt) ' IM "i~( ',4 ~ , ~ . · 6[ f~ sa~ura~ee, nlgn±y organic I' ~',~3ROWN nRAVSLLY SILTY SAND I ;~ ~,,.~ wet, co)bZes to ]4" sL~e ~?'.]:~ with steady seeeace, S ].OUghing cfi, ~' (SM) wet decreasing moisture cent }F~'~ on~ with depth ...... 7a~_on, interpolated from n .... , : .a~ by Unwin and Schoben dtd. 6-6-75 10" LOG OF T,t.:ST PZ? B ,~quipment John Deere ]3ackhoe Elev.qflon 984 + Do're , J[,:~lO,, ~-,~:.AC], SAND.. ,, ~,' ( ,, ~,,,,~ (SM) wet with cobbler; to 8" siz,' ~'~,~ Boulde~=,..~ to 20" at with ,J decreasing moisture content ,?,';RAY-GREEN SANDY SILT moist with slight gravel conten ~,, 7~.',"'~ }:IOWN CRAVE!,LY SAND (SP) mci_st NO. FREE WATER E~.~COU.~RED LOG OF 'a:s'rs P~TS n&}~ ~ PLAT7 KARVIEW SU3DIVISION .LOTS ]_&2~ ,,/IALLEY ~ ~° ~'oo" w RD. 2~"'"x N 00°01'00'' E 00~-' bxq4 ',1\~ ~ ot October 7, 1975 S-3~3]. - The Anchorage Municipality has received a petition from Gordon D. Unwin to subdivide approximately 2, acres of previously unsubdivided land into two lots. The petition area is located on the east side of Hideaway Drive, approximately 1/3 mile south of O'Maltey Road and 1/4 mile east of Hillside Drive. These lands are presently designated: previously unsubdivided lands located in the NWl/4, SW1/4, NWl/4, of Section 24, T12N, R3W, S.M., Alaska, and are proposed to be designated: Karview Subdivision, Letsland 2, by Unwin &Scheben. The petitioner haa ~6n~rred in a postponement of this case ~J{l'% .- ~h~ovember 4th meeting. Staff concurred in this postponement for ~ availability. soils and water ~ditional information on 3^l~JO A~'~3(]IH z%