The URL can be used to link to this page

Home My WebLink AboutHART Soils S-3463 GREATER ANCHORAGE AREA BOROUGH DEPARTMENT OF ENVIRONMENTAL QUALITY MEMORANDUM · January 14, 1975 TO: FROM: SUBJECT: Paul Cart Planning Department Chief Sanitarian Subdivision Plat Review For February 4, 1975 Meeting The Greater Anchorage Area Borough Department of Environmental Quality has reviewed the proposed plats listed below and has the following comments: A. Plats having public sewer and water available and meeting our requirements. 1. S-3579 Green Valley #2 2. S-3581 Stonegate Townhouse, Tracts lA and lB 3. S-3582 Simonian Subdivision, Tracts C-1, C-2 and D-1 B. Plats not having public sewer and water and meeting our requirements. 4. S-3462 Hart Subdivision Ail our requirements have been satisfied. The only questionable factor was the water table as reported in the soils test. However, field review shows that there is ample area to locate a sewer system on the southern portion of the lot and stay away from this area. The water table elevation in itself does not prohibit waste disposal at the test site. It just makes this particular site less desirable than other areas on the lot. 5. S-3550 Elmore Subdivision, Block 2, Lots 3A, 4A, 13A and 14A We have no objection to this proposal. The lots have already been subdivided at a previous time. This proposed action will actually add a small amount of area to each lot. ALASKA LAND DEVELOPMENT SERVICES 4546 BUSINESS PARK BOULEVARD ANCHORAGE, ALASKA 99503 PHONE (907) 274 -6191 or 274 -6068 January 8, 1975 Rolf Strickland Department of Environmental Quality Greater Anchorage Area Borough 3330 C Street Anchorage, Alaska 99503 RE: Hart Subdivision Case S-3463 Dear Rolf: Our soils analysis for this subdivision was made on samplings taken from a test hole made 72'+ North of South line Lot 93B and 65'+ East of West- line of the lot. Thank you for your call. Sincerely,' --.~ ' ~11~am R, T~cker WRT/dtn 4040 "B" STREET, ANCHORAGE., ALASKA 99503 PHONE: 907-279-2581 December 18, 1974 WO #16755 Alaska Land Development 4546 Business Park Boulevard Anchorage, Alaska 99503 Attention: Mr. Bill Tucker Subject: Hart Subdivzsion, Lot 93 Addendum No. 1 Dear Bill: This letter will confirm our several discussion regarding the percolation characteristics of the material on the sub3ect site. As you will recollect from our letter of June 29, 1974, it zs our opinion that the rate of flow through the F-1 materials above the water table is on the order of 1"/30 minutes. This causes that material not to be as desirable as one would normally associate with an F-1 soil. We do not see any reason why it cannot be used for a leaching field for a single family resident sewerage system.---In the · general context of the lot size which, I believe, is 1-1/4 acres and the area tested being in the low area---and the most poorly drained on the general site. However, we bring to your attention the possibility that one of the package units, that provides a more complete on-site sewage treat- ment system than the normal septic tank leaching field, be resorted to and that possibly a deep narrow trench or a series of deep narrow trenches rather than one single large leaching pit; would present your client with a more trouble free system than the conventional septic tank leaching pit system so common to the area. We trust you recognize our position in this matter, that while we see no reason why an on-site system should be avoided for a single family residence that we also are concerned that the owner recognize that the materials are not particularly permeable and may with time cause more problem than the collector sewer systems such as we enjoy in the corporate limits of Anchorage. $ 3 Alaska Land Development December 18, 1974 Page 2 We trust the foregoing is sufficient and complete to your immediate needs and fully expresses our concern that the project be considered in light of the reported good per- formance of the existing system on the other half of the subdivision. Very truly yours, HRL:rb S ~8.5 FEB ~ 1975 MATERIALS 1940 POST ROAD June 29, 1974 W.O. #16755 279-2551 Alaska Land Development 8730 Lake Otis Parkway Anchorage, Alaska 99.507 ATTENTION: Mr. Bill Tucker SUBJECT: 'Lot 93, Hart Subdivision Gentlemen: Transmitted herewith are the results of the subsurface investigation performed on the above property on June 19, 1974. Exploration consisted of one 15' test hole drilled by Denali Drilling, Inc., employing Nodwell mounted, Mobile drill, fitted with an 8", solid core, continuous flight auger. Grab samples were taken at 10' and'lS', by pulling the auger out of the test hole and re- moving the sample from the flights of the auger from near the bit. The soils were visually classified in the field in accordance with.sheets 1 through 5, following the text. This field classification was verified by visual review of samples based on'the same criteria, in the laboratory. The drilling was supervised and tke test hole was logged by B. D. Kenworthy, technician of Our staff. The test hole was logged as follows: Test Hole 1 El~ation: Bxisting Ground Depth in Feet From To 0.0' 1.0' 1~0' 2.0r 2.0' 4.0' 4.0' 11.0! 11.0' 15.0~ Soil Description, F-4, brown organic overburden F-4, brOwn sandx.~ravellX sil__~t, wet, soft, Pi+, F-4, grey sand~ gravel'l~ silt., wet, low to medium density, ML/SM F-l, grey very silty sandy, ~a~, low to medium density, fines ~re P'I+, GM F-2, grey silty sand, low to-medium density~%, MEMBER iQT Alaska Land Developmen: Page 2 June 29, 1974 Bottom of Test Hole: Frost Line: Free Water Level; Sampl~ 1 2 1S.O' Nono observed 11.0' Deptk 7Z]?,~ °f,~amplg, 10.0' GRAB iS.0' GRAB Remarks: 1.' Mb/SM is defined to mean more than 40% silt size and possibly 50%+ .2. Elevation: existing ground 3. Date of exploration: June 19, 1974 The seepage area required per bedroom by soil type (per the Greater Anchorage Area Borough) is as follows: Soil Type ',(Unified Classi,f,icatiop). ML SP SW GM Seepage AreaRequiFe~ 275 ft2 /bedroom 250 ft2 /bedroom 1SO ft2 /bedroom '125 ft2 /bedroom 225 ft2 /bedroom 85 ft2 /bedroom Soils requiring greater than 250 ft.2 /bedroom are not allowed in seepage pit area calculations (per the Greater Anchorage Area Borough). . The seepage area required at depth can be expressed as follows: Unified Soils Seepage Area Depth_ Classificatio~ ~equired 0.0' - 4.0' Mb/SM 4;0' - 11.0' GM 11.0' ' 15.0' SM Not Recommended 225 ft2 /bedroom (see note) 250 ft2 /bedroom - Not Allowable (below water table) S 346FEB 4 Alaska Land Development Page 3 June 29, 1974 Note the soils encountered between 4.0' and 11.0' meet the gradation require- ments to be classified GM. However, the staff geologist reviewing the samples believes that the percolation rate would be in excess of 30 minutes for one inch of fall. Enclosed are some excerpts from State and Borough ordinances which may be of value to you. For further restrictions, particularly with reference to loca- tion of the seepage pit we.call your attention to the Greater Anchorage Area Borough Ordinance 28-68. Please call if w~ can be of further service. Very truly yours, ALASKA TESTLAB,,~ John H. Lambe Approved: Harry R. ~ee, P.E. JML/vms Enclosures June 29, 1974 ,'~ .0. #16755 Alaska Land Development 8730 Lake Otis Parkway Anchorage, Alaska 99507 ATTENTION: Mr. Bill Tucker SUBJECT: Lot 93, Hart Subdivision Transmitted herewith are the results of the subsurface investigation performed on the above property on June 19, 1974. 'Exploration consisted of one 15' test hole drilled by Denali. Drilling, Inc., employing Nodwell mounted, Mobile B-50 drill, fitted with an 8", solid core, continuous flight auger. Grab samples were taken at I0' and 15', by pulling the auger out of the test hole and re- moving the sample from the flights of the auger from near the bit. The soils '~'were visually classified in the field in accordance with sheets I through 3, following the text. This field classification was verified by visual review of samples based on the same criteria, in the laboratory. The drilling was supervised and the test hole ]vas logged by B. D. Kenworthy, technician of our staff; The test hole was logged as follows: Test Hole 1 E].~ation: E~isting Ground Depth in Feet From To 0.0' 1.0' 1.0' 2.0' 2.0' 4.0' Soil Description F-4, brown organic overburden F-4, brown ~andy gravelly silt, wet, soft, PI+, ML/SM F-4, grey ~andy gravelly s~lt, wet, low to medium density, ML/SM F-l, grey very .silty sandy gravel, low to medium density, fines are Pi*, GM F-2, grey silt_z sand, low to medium density, S34 6 3 AU6 6 1974 MEMBER Alaska Land Developmen~ Page 2 June 29, 1974 Bottom ~f Test Hole: Frost Line: · Free Water Level: Sampl.~ 1 2 ? Remarks: 1S.O' ' None Observed 11.0' Depth 10.0' 15.0' ~?pe. of ~ample GRAB GRAB ML/S~] is defined to mean more than 40% silt size and possibly 50%+ Elevation: existing ground Date of exploration: June 19, 1974 The seepage area required oer bedroom by soil type (per the Greater Anchorage ' Area Borough) is as follows: Soil Type (Unified Classification) ML SM SP SI7 Seepage Area Required 27S ft2 /bedroom 250 ft2 /bedroom 150 ft2 /bedroom '125 ft2 /bedroom GM 225 ft2 /bedroom GlV 85 ft2 /bedroom Soils requiring greater than 250 ft2 /bedroom are not allowed in seepage pit area calculations (per the Greater Anchorage Area Borough). The seepage area required at depth can be expressed as follows: 0.0' - 4.0' ML/SM 4.0' - 11.0' GM 11.0' 15.0' SM Unified Soils Classification Seepage Area Required Not Recommended 225 ft2 /bedroom (see note) 250 ft2 /bedroom Not Allowable (below water table) Alaska Land Development Page 3 June 29, 1974 Note the soils encountered between 4.0' and 11.0' meet the gradation require- ments to be classified GM. However, the staff geologist reviewing the samples believes that the percolation rate would be in excess of 30 minutes for one inch of fall. Enclosed are some excerpts from State and Borough ordinances which may be of value to you. For further restrictions, particularly with reference to tion of the seepage pit we call your attention to the Greater Anchorage Area Borough Ordinance 28-68. Please call if we can be of further service. Very truly yours, Approved: Hb. rr~, R. ~6e, P.E. "- ..~ JML/vms Enclosures P'a'Be 15 Ordinance No. 28-68 (a) No s~epage pit excavation shall ex~end into th~ water table. Where ground Water is encountered, the bottom of the pit shall be backfilled with clean above the water table. (~) The top of all seepage pits shall be nq~ less .'than 18 inches below the fihished grade. (c.) ~e required absorption area of seepage pits shall be computed on the basis of percolation tests made in each vertical stratum penetrated. The .weighted average of the results shall be computed to obtain a design figure. Soil strata in ~l~ich the percolation rates are in excess of 30 minu~es per inch shall not be included in computing the · absorption area. (d) Seepage p~ts shall not be installed in areas where the percolation rate is greater than 30 'minutes per inch, i.e., in areas where more than 30 minutes is required .for the water in the test hole, after proper preparation, to fall one inch. :(e;) Table No. 4 shall be used to compute the required'seepage area for seepage pits. (~) The effective seepage area of a seepage pit Shall be the vertical wall area, based o.n dug diameteF, of the pervious strata below the inlet. (g) The lo. cation of seepage pits shall be such as to provide not less ~han the stated distances' from the followi, ng: age 16 Ordinance No. 28~68 TABLE NO. 6 : Any: Source o.f Domestic Water Supply 100 feet '4. Watermai.n or Service Line ~ 10' feet 5. Other Seepage Pits (3 times the diameter of the · .seepage pi%s.) 6. Septic Tanks (h) The seepage pit shall be lined w~th brick, . . ' . buildin'g tile, perforated precast concrete rings~ ~2#//,, ,, ./~/or other material approved by t'he health'authority. 4(~',P'.~u :.~q~,The ·space between the outside of the li.ni.ng and . .' .~.~.~ the soil shall be back~'illed with clean coarse J/P'~i ~ ~ gravel or s~milar mateb~al, The lining shall be ~2q'~v~surr°unded'°n all sides by at least.2 feet of (i) The sewer line draining the septic tank effluent to the seepage pit shall be. of cast iron from 'the seepage pit lining to a point not less .than 5 feet beyond the nearest undisturbed soil unless, suitable bedding material properly compacted is used to support the line. (j) The top of the seepage pit shall be covered . app.roved b'y the health authority. · :, :...~/~: :-~,. - ~':-. , ..'. .... ' .... , : -'..~' with a reinforced concrete, top or other material .Ordinance No. 28 (k) All seepage pits shall be provided with ..a cast iron siphon pipe of 4" diameter or larger. All siphon pipes shall be fitted with an air- 9.' Cesspools shall no~; be used for disposal of ~,uuse- hold wastes unless specifically authorized by..the health authority. (a)' Cesspools shall not be used in areas where ground water supplies are used for domestic purposes. (b) The construction of cesspools sh~ll follow the s. ame standards as those given for seepage pits. (C) Exemptions. 1. All septic tanks, drainfields, and seepage pits in use on September, 1968, are ex'empt from subsections (B) .(5), (B) (6), (B) (7), (B) (8) (b), (~) (a) (c), (B) (8) (d), (B) (e), and (B) (8) (~) of this section. Sec. 9-72 ItON t,rATER-CARRIED SEWAGE DISPOSAL SYSTEI.IS. (A) The construction and maintenance of earth pit pr.ivies shall comply ~with the following requirements. 1. Earth pit privies shall be loca'~ed at least 100 feet from any spring, well on other source of domestic watet~ supply; 100 feet from any stream, river or la:~.:e;' and l0 feet from any watermain, water service line or,property line. ' ' ' ~ "' 2: Earth pit pr~ivies shall be constructed 'as recommended in the Alaska Departmen~ of Health Document HSE. 722, ~ooooo ~ poe" o ~ I; F- z~ F-