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Home My WebLink AboutUPLANDS PH 2 S12373 Onsite File Uplands Ph 2 #512373 ♦., ,�, ' GE ENGINEERING PO BOX 240773 ANCHORAGE,AK 99524 522-7773 677-7766(FAX) December 7, 2017 Municipality of Anchorage Building Safety Division On Site Water and Wastewater Program 4700 Elmore Street Anchorage, AK 99507 Attention: Debbie Wockenfuss Subject: Uplands Subdivision, Phase 2, S-12373 Septic System Feasibility and Water Availability Study Dear Debbie: A petition has been submitted to subdivide one tract into three, forming the Uplands Subdivision, Phase 2 (Platting case S-12317).The parcel will be divided into individual lots with one of the lots currently occupied. We our presenting our findings that each new lot will have sufficient area and potential for on-site wells and septic systems. The property in general is moderately sloped, towards the south in general, at grades ranging from 10%up to around 35%. Most of the area is in the 10-20% range, with a few portions steeper than 25%.No septic systems are proposed on the steeper slopes or within 50' uphill of them. Tract sizes are greater than 3 acres each, and the attached site plan demonstrates that there is enough space available to meet separation requirements for the wells and future septic systems. Test holes were dug on November 13, 2017. One test hole was placed on each vacant tract in areas that seemed to be possible for septic locations, and an additional test hole was dug when presumably impermeable hardpan was found in one area at 8.5' down. Monitoring tubes were placed in the test holes, and groundwater checked over a week later, on November 22nd. The test holes were dug down to the hardpan at 8.5', or to 16.5' where only sandy gravel was encountered. No groundwater was found in any of the test holes. Test holes found no bedrock. Soils were fairly uniform in the area, consisting mostly of sandy gravel with silt (GM/GP). Percolation benches were constructed between 2-4' below the ground surface in each test hole. The percolation cavity in each bench was prepared and presoaked in accordance with municipal requirements. Again, results were very uniform in the area, with all perk tests results falling around 5 min/in. Individual test results are including in the attached test hole information. According to code, any percolation rate over 5 min/in equates to 12,000 SF of septic reserve area per lot, which has been designated Uplands Subdivision, Phase 2 S-12373 on the accompanying site plan (with the exception of the tract with an existing home that has a designed system in place). Although the groundwater monitoring was not done during the months when, historically, the water is at its highest, we are confident that the lack of groundwater discovered is typical of the area. We have examined records of test holes and septic systems on the lots immediately adjacent to the subject property to the west. All of them indicate either deep septic systems, or have soils logs that indicate no groundwater found. The information is compiled in the following table, and the logs are attached. Property Legal Groundwater readings Preuss#2, Block 3 Lot 2 Septic pit depths at 8' Preuss#2, Block 3 Lot 3 Septic field depth at 10.5' Preuss#2, Block 3 Lot 4 No groundwater in 2 test holes on 11/16/99, 15' deep Preuss#2, Block 3 Lot 5 No groundwater on 5/15/85, 16' deep No groundwater on 5/3/77, 16' deep Preuss#2, Block 3 Lot 6 No groundwater on 8/15/85, 15' deep No groundwater on 7/19/75, 12' deep With this historical information,we are confident that groundwater will not impede the design and construction of septic systems on this parcel. Additionally, we found well logs for six of the seven lots directly adjacent to the new subdivision on the west side that do not have connections to the water main. These are the closest wells to the properties, and are representative of the wells that would be drilled on these lots. Most of the lots have flow rates around 10 gpm, with one closer to 3 gpm. The information is collected in the following table, and the well logs attached. Property Legal Well depth (Ft) Flow rate (GPM) Preuss #2, Block 3 Lot 2 378 10 Preuss #2, Block 3 Lot 3 252 10 Preuss#2, Block 3 Lot 4 320 8 Preuss#2, Block 3 Lot 5 311 10 Preuss#2, Block 3 Lot 6 298 3.5 The properties to the north and east all have municipal water available to them. By far the majority are connected to the public water system. At least portions of those water mains were built in the 1980's, after most of the referenced wells were drilled and tested. It is likely that existing wells in those areas have been abandoned, reducing the demand on the aquifer. It is clear from this study that the aquifer in the area has the capacity to support new wells on the three properties on the proposed subdivision (the existing well on the property is a pit well and will need to be brought up to code). The smallest property is over 3 acres in size, and the larger two are more than 7 acres. The large surface area means that new wells will not have a substantial effect on the available aquifer. Any new wells will likely be drilled to 250-350' deep, Uplands Subdivision, Phase 2 S-12373 and will produced between 5-10gpm. The wells will not affect the operation or output of the existing wells in the area. Based on our field studies,research, and water monitoring completed to date,it is clear that all lots of the proposed subdivision are capable of supporting new wells and onsite septic systems. Sincerely, Benjamin Schiller, P.E. Attachments no p' •• !4L . ,:46144 4 ( 9n± c •* // Benja in Schiller • ��'Fc , r C 12592 •••k`��/ 1 • 1:1.04,\,.(c. tF� i °PROFESS10N MUNICIPALITY OF ANCHORAGE �i�\\,N d' � DEVELOPMENT SERVICES DEPARTMENT ��Pq�G..•• ;9�p�1�+ 4700 EL MORE ROAD ANCHORAGE, AK 99519-6650 ...fol.. .� �� *��/ SOILS LOG AND PERCOLATION TEST j ' Z // Benjami. Schiller • LEGAL DESCRIPTION: UPLANDS S/D 'tie •F�•,�!z 2�9Z,.••�� PERFORMED FOR: THE BOUTET COMPANY 1k F�PROFESST A�.s 11/13/17 `AV\��' DATE: PROJECT No.: PARCEL ID#: TECHNICIAN: J. MILLETTE Professional Engineers Stamp: DEPTH TEST HOLE #1 (feet) OB SLOPE SITE PLAN 1 2 3 SANDY GRAVEL. :.,!:. ' W/ SOME SILT 4 5 :; MUNICIPALITY OF ANCHORAGE • ��`.\\\\v` DEVELOPMENT SERVICES DEPARTMENT ��P, OF :4% 4700 ELMORE ROAD ANCHORAGE, AK 99519-6650 t 11 Jrb.. ... i':9 I *:49TH ‘ *`, SOILS LOG AND PERCOLATION TEST i ,, , . Be min Schiller • / UPLANDS S/D 0,�Fc�%. CEz2592 • ..'`44A/ LEGAL DESCRIPTION: I PERFORMED FOR: THE BOUTET COMPANY 1<<�9F0p O SS1*4., DATE: 11/13/17 PROJECT No.: 1,\\\��' PARCEL ID#: TECHNICIAN: J. MILLETTE Professional En'ineersScam.: DEPTH TEST HOLE #2 (feet) 1 03 SLOPE SITE PLAN 2 3 4 TIGHT • .-:,'•.; SANDY GRAVEL 5 .:,•;•K:::-..,;.; W/ SOME S'LT SEE SITE PLAN 7 ,, . .4. 8 — '' ' - .-. ' HARD PAN @ 8.5' 9 10 WAS GROUND WATER ENCOUNTERED? NO IF YES fid;WHAT DEPTH? - S DEPTH OF WATER AFTER MONITORING: NONE 11 DATE OFMONITORING: 11/22/17 12 - 1 13 DATE READING GROSS TIME NET TIME WATER TO NET DROP (MINUTES) (MINUTES) (INCHES) (INCHES) 14 I1/14 TEST HOLE PRESOAKED PRIOR TO TESTING: 15 1 5:45 0 16 2 6:15 30 53/8 5 % 3 6:16 0 17 4 6:46 30 5 %, 5X. 18 5 6:47 0 19 6 7:17 30 5X, 5 %4 20 PERCOLATION RATE: 5.7 (M1N/INCH) PERC. HOLE DIA. 6 (INCHES) TEST RUN BETWEEN: 2 FT. and 3 FT. COMMENTS: - MUNICIPALITY OF ANCHORAGE ��.oF\\��ti DEVELOPMENT SERVICES DEPARTMENT r�( S l) 4700 ELMORE ROAD ANCHORAGE, AK 99519-665 0 *�P'••Ti Jç 'T SOILS LOG AND PERCOLATION TEST g _��' gr /F•... Benja n Schiller • LEGAL DESCRIPTION: IE LANDS S/D r�+,slFgF. �.,2• 2x92.`��• i PERFORMED FOR: BOUTET COMPANY PROFESS\OA-.� DATE: 11/13/17 PROJECT No.: `,��\'��`�"�` PARCEL ID#: TECHNICIAN: J. M I LLE T T E Professional E.n:ineers Stain•: DEPTH TEST HOLE #3 (feet) 1 OB SLOPE SITE PLAN 2 :•. r 3 4 4 5 •; «�, SEE S:'.E Pia' 6 .. 7 • i •.• .. . . SANDY GRAVEL — 8 W/ SOME SILT t O -i:.::.!..:.:'•:' WAS GROUND WATER ENCOUNTERED'? NO l ,:-,_ IF YES(.WHAT DEPTH? - S !�:• n 4.L•�.y;�-i DEPTH OF WATER AFTER MONITORING: NONE I 11 ..%.:.•.•+•. DATE OF MONITORING: 11/22/17 12 •;::•':...? E :.1...-::•:...i.,: DEPTH To 13 '. : ' '' ;.. DATE READING GROSS TIME NET TIME WATER NET DROP (MINUTES) (MINUTES) (INCHES) (INCHES) 14 ,�" :';`-'!: II/IL TEST HOLE PRESOAKED PRIOR TO TESTING: 15—:!::•-•:::,•::::.:: I 7:30 0 16 2 8:00 30 6 6 17 • ... , 3 8:01 0 4 8:31 30 5 7/8 5 7/8 18 5 8:32 0 19 6 9:02 30 5 /8 5 7/8 20 PERCOLATION RATE: 5.1 (MIN/INCH) PERC.HOLE DIA. 6 (INCHES) TEST RUN BETWEEN: 3 FT. and 4 FT. COMMENTS: - Slopes Table 114' Number Minimum Slope MQeimufl Slope Area Color yt' 1 A VOX 1 25.007 222.367 438750.41 E OY 4+�.„ +o Sl8/i!!.�/ ig' j, Z per e .5 4 ,6 ,mLIQ 1lr..1 "„•� ? I / I PREU.S S :DIV ION I ' /( I / UNI No. 21 SS SU: V I,� s. E- AT S/�• 3 t/a B• SF P-E I1 /91Tc : 1.REU �• �tap NO 3 4LEG18LE ., ` I �� I� 4'Q4'29 1267. 0' • I ' 1- , ' a / y ,ti v '03't• w 1267 2' -1 itraw ' r�ildzi.„, _ \� , eLorK z/ y�Q/ • iii• CAP LMONU 7.419rigwrigUMI 5 2.14( 323.67' 40i•• rf/ 14' /50n.., 1 /11)/tr iit, iik ‘2 ',„ ). ' . 75' #40- :lp r b.,irlilml • r AC X57 AC e' Bic t . OriJ ... 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OCK / esti:. ,.• jSti.'4 1 0%f4,,, • d MOA Platting �t�a'ilk:. Y?�.z.• 3 cncs � hcse Case No. S- 12373 �ttt' � _ ." Septic Testnole Locctio - s 11 - 28 - 2017