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Home My WebLink AboutKENO HILLS ADDITION #9 S-11727Keno Hills 49 5-11727 ANDERSON ENGINEERING P.O. BOX 240773 ANCHORAGE, AK 99524 522-7773 September 22, 2010 Municipality of Anchorage Building Safety Division On Site Water and Wastewater Program 4700 Elmore Street Anchorage, AK 99507 Attention: Debbie Wockenfuss Keno Hills Addition No. 9 Subdivision, S-11727-2 Septic System Feasibility Study Dear Debbie: The owner of Tract Al, Keno Hills Addition No. 8 Subdivision intends to subdivide the tract into two lots and a tract. The lots front along Golden View Drive and are designed around the existing Tract Al. The new subdivision will be known as Keno Hills Addition No. 9 Subdivision. All of the parcels exceed 5.0 Acres in surface area with the tract 14.9 Acres. All three parcels will be served by a common access driveway which extends from Goldenview Drive to the east. The subdivision is located immediately east of Goldenview' Drive just south of Bluebell Drive. The ground surface of the lots slopes moderately from Goldenview at varying grades in an easterly direction to the eastern boundary of the subdivision. This slope is approximately 10% to 20%. All septic systems proposed for the lots will be placed in areas where the surface slope is less than 20%. The cross slope on the property is nearly flat. The proposed absorption systems are placed parallel with the contours at locations where the slope is the shallowest. A septic system is currently in place on Tract A-lA with a house and an operational well. This septic system has been operational for some time and shows no sign of deterioration. Test holes were placed on the proposed lots and tract in August of 2008 by Spurkland Engineering with a final test hole recently placed on Lot 12. Water monitoring has been ongoing with final readings scheduled for October 15 of 2010. The purpose of the test holes was to assess the underlying soil conditions and to determine whether septic systems could be placed on the lots to serve single- family homes. The test holes were placed to depths of up to 16' with no bedrock or impermeable lenses of material encountered. The locations of the test holes were determined in the field and placed in areas which would be most beneficial for septic system construction in the future. Percolation benches were constructed at various depths in the holes, but primarily 4' to 5' below the original ground Keno Hills Subdivision Addn. No. 9 September 22, 2010 Page 2 surface. A percolation cavity was prepared to determine the absorptive characteristics of the soils encountered. The cavity was presoaked in accordance with Municipal requirements and a percolation test performed. The results of the tests are included in the attached documentation. In every case silty gravel and sand (GM/SM/ML) was encountered to the bottom of each test hole. The percolation rate in this material ranged from less than 1 to 53 minutes per inch. All work was completed by Spurkland Engineering with the exception of the final hole on Lot 12 which was completed by technicians and engineers at Anderson Engineering. The results of the percolation tests and test hole logs are included as well as the water monitoring results. A monitor tube remains in place in each hole to determine the groundwater elevation over a period of time. Reserve areas were established for the two lots and the tract in the subdivision. The size of the reserve area was increased to 14,000 square feet from the requiredlO,O00 square feet for the percolation results obtained. The locations are shown on the attached drawing. Based on our field study and water monitoring completed to date it appears Lots 11 and 12 and Tract A-la of the proposed subdivision are capable of supporting an onsite septic system and well. The size of the homes to be constructed on the lots is not limited by any soil conditions found in our study. Copies of the test hole logs, percolation tests, test hole location map along with the repod generated by Spurkland Engineering and the contour map showing the surface topography of the property are included for your use. We hereby request your approval of Keno Hills Addition No. 9 Subdivision as designed with the septic system reserve areas at the locations shown. Sincerely, Michael E. Anderson, P.E. ~ ~ 49~h ~ ~ ~ ~, MICHAEL E. ANDERSON DEP'I~I (f~¢0 1 2 3 4. 7-- 8-- 9-- 2O MUNICIPALITY OF ANCHORAGE DEVELOPMENT SERVICES DEPARTMENT l+700 ELMORE ROAD ANCHORAGE, AK 99519-6650 SOILS LOG - PERCOLATION TEST I KENO HILLS ADDITION NO. 9, LOT 12 JANEY PIOEN LEGAL DESCRIPTION: PERFORMED FOR: DATE: 8/20/09 PARCEL ID#: OG/OL SILTY GRAVEL GM/GP DENSER WITH DEPTH PROJECT No.: TECHNICIAN: I EST nOLE A I A. HARALA SLOPE SITE PLAN WA S GROUND WATER ENCOUNTERED? NO IF YES ~ WHAT DEPTH%__ DEPTH OF WATER AE TEK MONITORING: NON~ DATE OF MONITORING: 9/15/00 DATE SEE SITE PLAN SEE SITE PLAN READING GROSS T ME NET T HE EWE%~'~RTO NET DROP (MINUTES) (MINUTES) (INCHES) (INCHES) TEST HOLE PRESOAKED PRIOR TO TESTING: 1 4:07 1.IY' 2 4:37 30 3.75" 2.62" 3 4:40 1.25" 4 5:10 30 3.75" 2.50" 5:12 1.06" 8/2O 6 5:42 30 3.56" 2.50" PERCOLATION RATE: 12 .(M1N/INCH) PERC. HOLE DIA, 6 .(INCHES) TEST RUN BETWEEN: 4 FT. and 5 FT. - , COMMENTS: TEST HOLE PRE SOAKED PRIOR TO TEST. TEST PERFORMED BY VETECH ENGINEERING TECHNICAL SERVICE. I, MICHAEL E. ANDERSON CERTIFY THAT THIS WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPLE GUIDELINES 1N EFFECT ON THIS DATE: ~- ZZ. -~' 0 Perform~ For. 8- 9- 10- 1% 13- 14- 15- 16- 17- 18- 19- MuniclpaJity of Anchorage Development Services Department Building Sa~e~y Olv~$1on (SO7) 343-7~04 Soils Log - PercOletion Test Slope Site Plan Read~g Dal~ Gross Time Nel Time D~pth to Water Net PERCOLATION ~TE '~ j (mlma~} PF-.RC HO~.E DIAMETER 7- 8- g- 10- 11- 1:2- 13- 15- 17- 18- 19- , Municipality of Anchorage DeveJopmen/$~rvices Department Building Safely Division (907) 343-7904 Soils Log - Percolation Test Performed Foe: ,"To. n ~. u $'A~. WAS ~-ROLIND WAYER ENCOUNTERED? IF yES, AT WHAT DEPTH~ Reading Dat~ (~ross Time Net Time ~ "Jto' , .... . u ~l~ 30 ~;~ 13'/~ '~ 3 ?h~'~ ~EJ~COLATION RATE '~_~ ~ ml~u~um~l P~RC MOLE DIAMETER-- ( ~ PERFORMED IN ACCORDANCE Wt'~H ALL STATE AND MUNICIPAL GUIDEI. I~ES JN EFF£CT ON THIS DATE. DATE: Uuni'cJpalJty of Anchorage Development Services Department Budding Safe~y Division On-Site Wa~? and Wastewale¢ Program 4700 South B~ag~w SL (907) ~3-7g04 Soils Log - Percolation Test Performed For. .J~.~ p_,~ ~ ~ ~ ~ 11- 13- 14- 15- 17- 18- 19- 20- , Town~hlp, Range, Seation: Slope Plan Reading Date Gross Time Nat Time L3ep:h lo Water Net Drop OLa, TIO N RAT~ ~'.~ (miau~) PEI~C HOLE DIAMETER CC AND MUNIC PAL ~ PO/PO BD~d IS£ 9P~SPSZ06 PE:~[ 0~0~/90/80 ANDERSON ENGINEERING P.O. BOX 240773 ANCHORAGE, AK 99524 522-7773 677-7766 (FAX) November 3, 2010 Municipality of Anchorage Building Safety Division On Site Water and Wastewater Program 4700 Elmore Street Anchorage, AK 99507 Attention: Debbie Wockenfuss Subject: Keno Hills Subdivision Addition No. - S-11727-2 Test Hole Water Monitoring Dear Debbie: The results of the water monitoring on Keno Hills Subdivision Addition No. 9 are as follows: Test Hole No. Lot No. Depth 8~20~08 1011612010 TH1 A-IA 14' 6' 6' TH2 11 14' 5.8' 5.8' THA 12 I 13' 8' Sincerely, Michael E. Anderson, P.E. GOLDEN PARK q S O0'03'O0"E 987.76' ANDERSON ENGINEERING P.O. BOX 240773 ANCHORAGE, AK 99524 522-7773 677-7766 (FAX) November 1, 2010 Municipality of Anchorage Building Safety Division On Site Water and Wastewater Program 4700 Elmore Street Anchorage, AK 99507 Attention: Debbie Wockenfuss Subject: Keno Hills Subdivision, Addn. No. 9 - S-11727-2 Lots 11 & 12 and Tract A-lA Water Availability Study Dear Debbie: We have collected information on several wells in the area of the proposed Keno Hills Subdivision, Addition No. 9 to estimate the possible depths and production rates of wells to be constructed in the future on Lots 11 and 12 and Tract A-lA. Lots have been developed on all sides of the new subdivision with producing wells on each lot. In all cases the wells are shallow in comparison to most wells in the Anchorage area with the deepest at 305' and the shallowest at 38'. Bedrock was noted in nearly every well and it is suspected all of the wells encountered bedrock especially the shallower wells. Very little information is available on the lots immediately west of the subdivision in Pennington Park Subdivision. Lot 8 just west of Tract A-lA is 177' deep with a production rate of 3.5 gallons per minute as tested in 1993. All of the lots along the west side of the subdivision are thought to be similar to Lot 8 with similar production rates. The lots in Keno Hills Subdivision, No. 6 directly east of Lots 11 and 12 range from 127' deep to 305' deep and are all founded in bedrock. The production rates on these wells range from 2.2 to 4.0 gallons per minute. The well directly south of Lot 11 on Tract B, Keno Hills Subdivision, Addn. No. 9 S-11752 November1,2010 Page 2 Keno Hills Subdivision1 Addition No. 7 is 185' deep with a production rate of 4.0 gallons per minute. The wells to the north of the subdivision are very shallow ranging from 38' to 166' below the surface. The production rates of the wells range from 3.5 to 10.0 gallons per minute as noted on the well logs. The logs further indicate no bedrock encountered in this area, but productive sand and gravel lenses saturated with water. KENO HILLS SUBDIVISION, ADDITION NO. 9 WATER AVAILABILITY STUDY WELL LEGAL DESCRIPTION DEPTH PRODUCTION - LOG PRODUCTION - TEST Keno Hills, Block 2, Lot 1 38.3' 10.0 GPM Keno Hills, Block 2, Lot 2 48' 20.0 GPM 3.5 GPM Keno Hills, Block 2, Lot 3 51' No Log Keno Hills No. 6, Lot4 170' 2.5 GPM 2.17 GPM Keno Hills No. 6, Lot 6 226' 4.0 GPM Keno Hills No. 6, Lot7 305' 8.0 GPM 4.1, 4.5 GPM Keno Hills No. 6, Lot 8 127' 3.0 GPM 2.4 GPM Keno Hills No. 7, Tract B 185' 4.0 GPM Keno Hills, Block 1, Lot2 166' 6.0 GPM Keno Hills, Block 1, Lot 3 95' 2.9 GPM A water source is currently available on Tract A-lA. It appears to be a hand developed artesian water box. Water is flowing to the surface and piped to the existing house on the property. The presence of the water indicates that with sufficient development a well could be drilled to a depth exceeding 40' which would deliver more than enough water to meet Municipal Code and satisfy the water requirements of the house. It is obvious from our study that any wells to be constructed in Keno Hills Subdivision, Addition No. 9 in the future will be placed to depths of less than 200' and will probably be founded in bedrock. The depth of the bedrock is unknown, but may exceed 50'. It is also possible bedrock may not be found as noted on the lots to the north. The Keno Hills Subdivision, Addn. No. 9 S-11752 November1,2010 Page 2 production rates will be sufficient to support a four bedroom home and can be expected to be between 2 and 4 gallons per minute. Sincerely, Michael E. Anderson, P.E. Attachments