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Home My WebLink AboutGEORGE SEHM LT 18 6oro 36 Se.k m s ,,;_,<,. MUNICIPALITY OF ANCHORAGE ,~._,/ DEPARTMENT OF HEALTH & ENVIRONMENTAL PROTECTION ENVIRONMENTAL ENGINEERING DIVISION 825 L Street - Anchorage, Alaska 99501 Telephone 264-4720 ON-SITE SEWAGE DISPOSAL SYSTEM AND/OR WELL INSPECTION REPORT DISTANCE TO: t~(~ / Abs°rpti°"'~arz Manufacturer L q. cai Inside length Dwelling Materi Width NO. OFr~DROOMS PERMIT N~?~ ~6 I IF HOMEMADE: Well PERMIT NO, DISTANCE TQ: Manufacturer Material Foundatij~ Nearest 2~in TMO:ta:r ::ln~e r~at~:: Tren~v~th DISTANCE TO: Wel/~ ~OO t No. of lines/ Le,~g~ o'~e~,~el Top of tile to finish grade~,~ Length inches inches Width Depth No. of comZments Liquid depth : Liquid capacity in gallons PERMIT N~l~ ~g~ Total effec~.j~e.A~s.~r~otion area PERMIT NO. Type of crib Crib diameter Crib depth Total effective absorption area Well Building foundation Nearest lot line DISTANCE TO: Class Depth Driller Distance to lot line PERMIT NO, DISTANCE TO: Building foundation Sewer line Septic tank Absorpt on area(s) I OTHER PIPE~/IA'[ERIALB~ SO, TESTRAT .- DATE LEGAL 'T'HE( L.E:?.,II3TH D I h't~:~:i'.,l'.:::; I Cff',i :!: :!ii; THE LE?.,{(.'.:iTI"! ( :[ I',1 FI!E6:T ) Qr:: THE 'TI:;~:E;I'.,!CH Oi:;;: DF:I:::i i ?.,il:::' ! ~U....D. 'TI...IiE DEF'TH OF FI 'TI::;iE:h,!C,LI O!:;i: F'!T :!:S THf!i: D!:STI:::II'.,!I:::I.!i; !3iE'T'HE!!i~:N THE l:iil:;i:Cil...IN[) I::11'.,I[::, 'THEi: E',OT"i"Oi'"! OF' 'T'HiE i~!:;x:(:::!::!'v'!:::!"[' :i: i:::1i'.,! ,:: ]: l'-,! ,9:'lii~!:ii:"!" ::,. TI..-!.EF'.F~. ! :5 NO SE'T 14 i'i:::,TH FO!~: "i"t:;.':IENCHIES. TI...IE GFU:I',,,'I.EL C, EF'T!..-! :i:S 'T'I.!E hl:.I.'N~i'"iUH DIL'P'!"H OF G?;i:i:::tVEL. Fi',E:THiE.~EN "!"HiZ EdJTF'F!!...L. P:i:f::'~i: FINE:, THE: B(:rT'TOI"! 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I (:::!iEl:;i:'l" i I:::'"r' THI:::IT ::!..: :i: F::IH F'I:::IMII..~ZFIF~: !.,.!!TH THE: F:E(N...I:!iI::;'.EHEi:NT:~; l:::'O!:;~t ON"~'Si'TE: SE!.,.h~EI:;;!'.::~; I:::!I",![) I,.!E:L.L..i~ii; .~::iS SET i:::'O!:;Ui"H B"/ THE I'"ILiNIC:[F'F:IL!T"/ OF' !:::!t",!(::HOI::~:I::iG!E. :2: ! 14 :[ L.L. :[ NSTFiLL. THE ::5","STfii:H :!:i",i I:::i(]:C()F.':i~:,i::ii",!i:]:~!( i4 i TH THE :i!:: ! I..INC, i!:~:I::~:!'~;TI:':iI",IE.', THFFf' "I"Hi~: Oi",!-SITtE ':?;i~H.('i:F:'. :!!i;"?".i~;TIZH HF!V F:Ei:(;!L!:I:F:~ii: i:!!:!",!M:::!.~;ii(:iiEMEN'T :i:!:::' THIE RESif)i:Ei",iCE I!!.; I';i:I!'EHOC'IELIi:::D 'T'(:) !I",!CL..IJDt!E MO!::i:E TH!:::!i",! ~i: !!3iEE;'fi~i(:)()l¥1~!i;. Steven A. Johnson( '~,P.O. Box 76 Chugiak, AK 99567 Phone: 907-688-3085 SOILS LOG - PERCOLATION TEST [] SOILS LOG PERCOLATION TEST PERFORMED FOR: 2- SLOPE DATE PERFORMEO: SITE PLAN 10 11 12 13 14 15 16 17 18 19 2O COMMENTS TB~_ Iq' WAS GROUND WATER S ENCOUNTERED? //~/~ L O P E IF YES, AT WHAT DEPTH;' Gross Net Depth to Net Reading Data Time Time Water Drop 72-008 PERCOLATION RATE ~/-~ {mlnutes/inch} TEST RUN I~E'I'WEEN q , FT AND ~ FT STEVEN A. JOHNSON and Associates P.O. Box 76 · Chugiak, Alaska 99567 · (907) 688-3085 Dear Realtor: Thank you for expressing an interest in our services. Enclosed is the information regarding percolation and adequacy tests. In each case I've attempted to explain the theory behind each of the procedures as well as the practical aspects of performing the service in the field. PERCOLATION TESTS Percolation tests are run in order to determine the ability of the soil to absorb water (effluent) produced by an on-site septic system. The complete on-site septic system is made up of two parts: the septic tank, which is a water-tight tank with a minimum capacity of 1,000 gallons~ and the drainage area, which is a trench or a pit filled with coarse gravel. In operation, raw sewage enters the septic tank through the inlet. Non-oxygen breathing (anaerobic) bacteria attack the solids and digest them, producing a sludge which settles to the bottom of the tank and effluent which exits the tank through the outlet. The effluent then enters the drainage area where it is absorbed by the on-site soils. The drainage area can be one of two designs depending on the permeability of soil present and when the system was installed. The most simple drainage area design is the seepage pit. Most homes built prior to 1974 had this type of system installed. In its most simple form, i% was a spruce log crib buried directly in the on-site soils. In later designs, concrete rings replaced spruce logs and coarse gravel was used to surround the rings prior to backfilling. Seepage pits are now normally used only where the soil is very permeable or where the lot is too small to permit installation of the longer seepage trench or drainfield. A seepage trench or drainfield was installed for the majority of homes constructed after 1974. It differs from the seepage pit in that instead of a pit with concrete rings, it makes use of a trench containing a perforated distribution pipe (see enclosed design sheets). As in the seepage pit, coarse gravel is used to line the excavation prior to backfilling. The length and depth of the seepage trench can be varied to fit the soil and water table conditions found on the site. There is no basic difference between the two, other than an exceptionally long, shallow seepage trench is generally called a drainfield. Consulting services for: On-site water and sewer systems, geotechnical and mineral exploration programs, site suitability studies No matter what type of drainage system is installed, the design is based on: 1) the permeability of the on-site soils as determined by the percolation test; and 2) the amount of fluid put into the system each day. The basic types of soils are classified as shown on the enclosed sheet issued by the Municipality of Anchorage. The soil classifi-- cation system is based upon the grain size of the most common particles present. As a general rule, the more sand (S) and gravel (G) present the higher the permeability; the more silt (M) and clay (C) present the lower the permeability. The amount of effluent the system must handle is directly propor- tional to the number of people using the system. A conservative assumption for water use is 75 gallons per day per person. At an average occupancy rate of two people per bedroom, this yields an average of 150 gallons per ~ay per bedroom. The ratings in square feet per bedroom (ft) shown on the soil characteristics chart make use of this assumption. As can be seen on the char~, a well graded gravel (GW) soil will require 85 square feet (ft) of contact area in the trench to absorb the 150 gallons of effluent, produced by the two residents. A less permeable silty gravel (GM) soil requires 225 ft~ of contact area, or almost three times as much to absorb the same amount of effluent. Total absorption area is obtained by multiplying the number of bedrooms by the soil rating. In the field, the percolation test can be performed one of two ways. In either case a backhoe is used to dig an inspection pit to a depth of 16 feet or greater. If t~e soils encountered classify visually at a rating of 150 ft~/bdrm or less, a weighted average is taken of the ratings for the soil(s) encountered and the test is completed. If the soil(s) have a weighted average of 150 ft2/bdrm or greater, we are required to run a percolation test at the depth in which the drainage system will be constructed. The most common method is to have the backhoe operator cut a ledge in the side of the inspection pit. A two foot deep hole is then dug on the ledge and the test begun. The test requires filling the hole with clean water and then measuring the rate of fall of the water over a three hour period or until the rate of fall has stabilized. Once a percolation rate in minutes per inch of fall has been established, it can be used ~o convert the rate of fall to an absorption area rating in ft /bdrm. I am currently charging $45.00 per inspection and $90.00 per percolation test. The backhoe charges usually run from $125.00 to $200.00 per test on a one-at-a-time basis. Under average conditions the backhoe can dig and move on two to three holes per hour. This would bring the price per test down to $115.00 to $180.00. If we could do five or more tests in one area, I would drop my rates to $30.00 for an inspection and $60.00 per perc test. ~100.00 to $130.00 per perc test. No. of Tests in Same Subdivision *Note: This would result in a maximum price of approximately In summary~ Inspection 1 $190100 2-4 115.00 5'& up 100200 *Estimated Price Each Including Backhoe Perc Test $230.00 180.00 .130.00 Backhoe rates vary from area to area. ADEQUACY TESTS Adequacy tests~are performed on existing systems~ They are required by lending institutions before loan approval. Currently, any system over four years old must be tested. The purpose of the adequacy test is to determihe whether or not the drainage system will accept the daily effluent volume pro- duced by the home. In order to pass, the system must absorb 150 gallons per day per bedroom. In addition, it must be able to absorb 30% of the daily volume in four hours. For example, the septic system for a three bedroom home must absorb 450 gallons over a 24 hour period. The drainage system must also be able to absorb 135 gallons within the first four hours of the 24 hour test period. The test procedure for seepage pits and drainfields are as follows: Seepage Pit Seepage pits are .tested by adding twice the estimated daily use volume (900 gallons for a three bedroom home) to the seepage pit in 200 gallon increments. The fluid level in the pit is then measured after each 200 gallon increment. This information is then used to calculate the storage capacity of the system. After the test volume has been added, the septic tank is pumped and the fluid level in the pit is measured every half hour for four hours or until-the surge volume has been absorbed. The final reading is made 24 hours after the initial reading. In order to pass, the system for a three bedroom home must absorb 450 gallons in a 24 hour period and be able to absorb 180 gallons within the first four hours. ~. Drainfield Drainfields are tested by adding the estimated daily use volume to the drainfield at a flow rate not to exceed 10 gallons per minute (gpm). The fluid level in the septic tank is monitored while adding water to the drainfield. If the fluid level in the septic tank rises more than one inch, the flow rate is cut back until the fluid level in the septic tank stabilizes. The time required to deliver the test volume will determine the absorption rate for the septic system. The procedure is followed on two consecutive days; the data for day II is used to compute the system's absorption capacity. Water for both the seepage pit and drainfield test is hauled in by a septic pumping service. In both tests, the septic tanks are pumped upon completion. Rates for performing the adequacy tests are as follows: Professional Services Seepage Pit $ 150.00 Drainfield 150.00 Pumper .Total $100.00 $250.00 150.00 300.00 The drainfield test is more expensive in that we must return to the system on three consecutive days. I normally use Rent-A-Can in the Chugiak-Eagle River area and Isaacs in the Anchorage area for pumping services. I hope this information answers more questions than it raises. Should you have any questions please don't hesitate to call. Sincerely, Engineering Geologist SAJ/kcj i ~ MUNICIPALITY 01- Ar~.MU~A~= DEPARTI~I~NT OF HEALTH & ENVIRONMENTAL PR~ro~('ECTION Telephone 264-4720 PRE-INSPECTION CHECKSHEET - TYPICAL TRENCH ON LEVEL TOPOGRAPHY MINIMUM WELL CLASS A, B. CLASS C ;DISTANCES: PUBLIC -- OVER 25 SERVICE OR PUBLIC -- UNDER 25 SERVICE OR MORE THAN 15 CONNECTS LESS THAN 15 CONNECTS INDIVIDUAL WELL TO TANK 200' TO TANK 150' TO TRENCH 200' TO TRENCH 150' TO TANK 100' ON THE S/D PLAT. ADEQUATE ENGINEERING PLANS ARE' REQUIRED. USED PERFORATED PIPE ~~ PLASTIC PIPE ASTM D3034 MAY BE - ST IRON {PERFORATIONS DOWN) IN PLACE OF THE CA V~ ~ ~ / '4 I[~: SOLID PIPEWITH CAP · . 41~ ~BOVE T-JOINT ,m'J ALL CLEANOUTS MUST COME AT LEAST TO GROUND LEVEL []PERFORATED PIPE INSTALLED LEVEL I--]SEEPAGE TRENCH INSTALLED ACCORD- ING TO SOIL TEST [--ISEPTIC TANK .MUNICIPALITY APPROVED [] INLET AND OUTLET OF SEPTIC TANK WATERTIGHT [~]TRENCH INSTALLED ACROSS SLOPE [] 4" SEWER PIPE OTHER THAN CAST IRON OR EQUIVALENT REQUIRE- MENTS SHOULD HAVE A 1500 LB. CRUSH STRENGTH NOTE: [] 100' MINIMUM FROM TANK AND TRENCH TO RIVER, LAKE OR STREAM ,, ,,, .,. ~, ',., -,~_ ~ ~ - .... t.~:~ ..... .... ' ........ .'eUz;:)'~ ..... "" .... ....... ,~,m ~PCR m " ' ~ - ~.~~ EARTH BACKFILL · -~:" ,,,, ...... ,..-......,. ' "- ' :'; % :.' .-:' ~: q.'h~(/ ?.' SCREENED GRAVEL ~,[~ ....... ~~: - , ~~- ~ . ~ .~., ....... / .......,~ .~~ .. ....... -~ .. MUNICIPALI~TY OF ANCHORAGE Health and Environmental Protection SOILS TEST Soi~'testing of each residential lot establishes sewer system design criteria. Testing is usually conducted by two(2) methods: (a) Percolation Test - water absorption rate is determined by using an augered hole sixteen(16) to twenty(20) feet in depth and filling it with water. This test is accurate for all types of soils. (b) Visual analysis is an excavation site of sixteen(16) to twenty(20) feet in depth. This is accurate for gravelly type soils ONLY. A percolation test is required if the visual analysis shows soils rated greater than 150 square feet per bedroom. (c) In all cases, the test must be run to a depth of four(4) feet below the bottom of the proposed disposal system. This is to ensure the system is'at least four(4) feet above any water table. Soil tests determine the ability of soils to absorb sewage. The on-site sewer system design will incorporate total sewage production and required absorption area for each residence. I. GRAVELS ~q - well graded gravel & sand GM - silty, sandy gravel GP - poorly graded gravels or gravel-sand RATING 85 sq.'/bedroom 225 sq.'/bedroom 125 sq.'/bedroom II. SANDS ae SW - well graded sands & gravel SP - poorly graded sand SM - silty sands 125 sq.'/bedroom 150 sq.'/bedroom 250 sq.'/bedroom III. SILTS A. ML - silt, fine sand mix 275 sq.'/bedroom IV. CLAYS A. CH - clay, silt 'and mix 350 sq.'/bedroom *Percolation test required on soils greater than 150 square feet per bedroom. 4/77 I · sec. coW.. ANCHORAGE PRECINCT Anchorage, Alaska '~zstrict Recorder . .~.~