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Home My WebLink AboutGLASSING RIDGE S12593Onsite File Civil Engineering and Surveying Consultants 1345 Rudakof Circle, Suite 201 Serving All of Alaska Anchorage, Alaska 99508 FAX: (907) 338-5386 Phone: (907) 337-3330 September 24, 2021 Deb Wockenfuss Municipality of Anchorage Development Services On -Site Water and Wastewater Program P.O. Box 196650 Anchorage, AK 99519-6650 Re: Glassing Ridge Subdivision, Response to Comments Ms. Wockenfuss, Thank you for your comments on the proposed Glassing Ridge Subdivision, dated 9/8/21. We have reviewed them and would like to offer the following responses: Comment #1— Substantiate that there is adequate and safe potable water for each proposed lot and neighboring lots. Response - The proposed Lot 58B has an existing well at the top of the embankment, near the south property line, that was drilled in 2019 to a depth of 75 ft. Well production was found to be 30 gpm, and nitrates tested at 3.96 mg/L. It is reasonable to assume the proposed Lot 58A will be able to construct a well to pull water from the same soil strata. The flow is adequate, and the nitrate levels are below the EPA standard of 10 mg/L. Other surrounding wells: o The existing well on Mariann Lot 73A (bordering lot to the south) was drilled in 1982 to a depth of 81 feet. Well production was found to be 30 gpm. An inspection in 1995 found the well production to be greater than 6.4 gpm and the nitrates to be 0.12 mg/L. o The existing well on Lot 8A (across the road to the east) was drilled in 1978 to a depth of 88 feet. Well production was found to be 30 gpm. An inspection in 1987 found the nitrates to be 0.14 mg/L. o The existing well on Zed Lot 1 (lot to the north) was drilled in 2008 to a depth of 61 feet. Well production was found to be 25 gpm. An inspection in 2014 found the well production to be greater than 5.3 gpm and the nitrates to be 1.36 mg/L. Glassing Ridge Sub 'd — Response to Comments September 24, 2011 Page 2 of 2 Comment #2 — Substantiate the capability of the proposed lots to adequately dispose of wastewater, see AMC 15.65.405 for requirements. Response - The proposed Lot 58B has an existing 3 bedroom home served by a septic system, near the future property line, that was constructed in 2019 (OSP 191327). Three test holes were excavated to a depth ranging from 18 to 21 feet in the design of this system, with no groundwater observed and percolation rates varying from 13 min/inch to 59 min/inch. Ultimately, a 56'L x 3'W x 9'D deep trench was constructed with an application rate of 0.45 gpd/sf. The attached map shows the potential location for a drainfield if a fixture home on Lot 58A is constructed at the top of the embankment. With a well .located in the northeast corner of the property, there would be adequate space to construct a primary (and replacement) deep trench disposal field matching the dimensions of the existing trench to the south. Much of the potential trench lies within the boundary of Test Hole #2, which had the most favorable percolation rate of 13 min/inch. If necessary, an advanced treatment system could be used to minimize the footprint of the drainf eld. The example deep trench could be shortened to 13'L in this scenario. If you have any questions, please contact me at 337-3330. Sincerely, VEI CONSULTANTS Scott T. Roel s, Attaclunent : Drawing — Potential Well / Drainfield for Lot 58A Civil Engineering and Surveying Consultants 1345 Rudakof Circle, Suite 201 Serving All of Alaska Anchorage, Alaska 99508 FAX: (907) 338-5386 Phone: (907) 337-3330 April 2, 2021 Municipality of Anchorage Planning Department P.O. Box 196650 Anchorage, AK 99519-6650 Re: On -Site Sewer and Soils for Lot 58, Section 5, Township 15N, Range 1 W, S.M. (Grid NW1457) Narrative To whom it may concern, VEI Consultants was contracted in 2019 to design an onsite wastewater disposal system at the above referenced property. A new three (3) bedroom single family residence was constructed and approved on the property in 2019. As shown on the attached site plan the new house with well and septic system is located on proposed Lot 58B. As part of this work a test hole was located on proposed Lot 58A for this soils investigation. Soils VEI conducted field investigations including surveying, digging test pits, performing percolation tests and groundwater monitoring. The Soils Log—Percolation Test for Test Hole #2 is attached. No groundwater has been observed in these test holes/monitoring pipes, and soils logs from surrounding properties led us to believe that groundwater is not an issue in this area. Still, we required the contractor to extend all three test holes (if necessary) to verify that there is no groundwater or impermeable strata within 6 feet of the bottom of the trench. The percolation tests were perforned using a falling head method (never exceeding the 8" of head outlined in code) and the percolation rate was calculated using the entire test (total minutes / total inches). We performed the tests multiple times throughout the day and we witnessed repeatable results. Only the last test of the day is provided on the soils log. Therefore, we are confident that we calculated conservative percolation rates. Surface Water & Topograpliy There are no surface waters within 100 feet of the proposed system. Additionally, no seasonal surface water was observed collecting anywhere on the property. The general On -Site Seiner and Soils Jor Lot 58 April 2, 2021 Page 2 of 2 slope of the lot is from southeast to northwest at a grade ranging from 2%-10%. An embankment, with a height of 50 feet and slopes between 40% to 70%, runs down the center of the property from the southwest to the northeast. There is ample space for an absorption system 50ft back from the embankment. If you have any questions, please contact me at 337-3330. Sincerely, VEI CONSULTANTS Scott T. Roelfs, P Attachments: Overall Site Plan V=100' Soils Log TH #2 72 58A 59 POTENTIAL DRAINFIELD LOCATION W/ REPLACEMENT 58B / �.., THy3 73A 0 Q ISTING SEPTIC OF ��SYSTEMS / ................ AMP Vis® AW 2: ' 9th ®.....: ............................. . ...80 r SCOTTT OE CE 4 �•_AV Air AV 1414® 4111lk RADIUS s I / 73B , yi T 1 VEI CONSULTANTS 1345 RUDAKOF CIRCLE POTENTIAL WELL / DRAINFIELD FOR LOT 58A VEI LOT 58A AND 58B GLASSING RIDGE SUBDIVISION Consultants HORZ SCALE: -100' I DATE: 12/30/22 1 GRID: NW1457 Pg 1 OF 1 EXISTING SEPTIC `POTENTIAL /% SYSTEM WELL I LOCATION / 3 � "q0 USABLE AREA j 2455 SF ` EXISTING 8A SEPTIC SYSTEM \ RADIUS s I / 73B , yi T 1 VEI CONSULTANTS 1345 RUDAKOF CIRCLE POTENTIAL WELL / DRAINFIELD FOR LOT 58A VEI LOT 58A AND 58B GLASSING RIDGE SUBDIVISION Consultants HORZ SCALE: -100' I DATE: 12/30/22 1 GRID: NW1457 Pg 1 OF 1 -VElConsultants Civil Engineeritrg and Surveying Consultants Serving All of Alaska SOILS LOG - PERCOLATION TEST 1345 Rudakof Circle, Suite 201 Anchorage, Alaska 99508 FAX: (907) 338-5386 Phone: (907) 337-3330 PERFORMED FOR: Oliver and Venita Moore DATE PERFORMED: 6/26/19, extended 9/25/19 LEGAL DESCRIPTION: Lot 58, Sec 5, T15N, R1 W, S.M. TOWNSHIP, RANGE, SECTION: T15N, R11V, Sec 5 PERFORMED BY: Scott Roelfs, P.E. TEST HOLE No. TH #2 SLOPE SITE PLAN 0- DEPTH (FEET) Net Time (mfn.) GROUNDWATER ENCOUNTERED: ® -- Topsoil ■ YES DEPTH TO GROUNDWATER: 2—""r.,e...: 14:52 SW sand, ® ❑ some gravel NO YES SP 4 :®:-':co' fine sand, 5- ® some gravel 5 15:14 5 6- 3/8 6 7- 9 3 7/8 8- 7 15.30 9- 4 3/8 1/2 10- ,. SP 11- '! fine sand 12- 7-- 5 1/2 13 - 13- Is - Is- 16 - 6-17- 17 - 6/26/19 18- 1s- 20 - •:"' Y 9/25/19 21- TOTAL DEPTH OF TESTHoLF_ 21.0 Net Time (mfn.) GROUNDWATER ENCOUNTERED: ® ❑ 14:38 ■ YES DEPTH TO GROUNDWATER: 2 14:52 GROUNDWATER ENCOUNTERED: ® ❑ (After Monitoring) NO YES DEPTH TO GROUNDWATER: 3/4 4 MONITORING DATE 7 29 19 8 2 7/8 5/8 5 15:14 TOTAL DEPTH OF TESTHoLF_ 21.0 Net Time (mfn.) GROUNDWATER ENCOUNTERED: ® ❑ 14:38 NO YES DEPTH TO GROUNDWATER: 2 14:52 GROUNDWATER ENCOUNTERED: ® ❑ (After Monitoring) NO YES DEPTH TO GROUNDWATER: 3/4 4 MONITORING DATE 7 29 19 b.5 4— a- 0 a - 0 V) Date Rearing Gross Time Net Time (mfn.) Depth to Water (inches) Net Drop (rMhes) 6/26/19 1 14:38 0 2 14:52 14 1 1/2 1 1/2 3 15:01 9 2 1/4 3/4 4 15:09 8 2 7/8 5/8 5 15:14 5 3 1/4 3/8 6 15:23 9 3 7/8 5/8 7 15.30 7 4 3/8 1/2 8 15:40 10 5 5/8 9 15:50 10 5 1/2 1/2 PERCOLATION RATE 13.1 (minuteaAnch) PERC HOLE DIAMETER 6" TEST RUN BETWEEN 6.0 FT AND 7.0 FT COMMENTS: Pre—Soak 4hrs Extended from 18.0 to 21.0 on 9/25/19 PERFORMED BY VEI CONSULTANTS. 1, SCOTT T. ROELFS , CERTIFY THAT THIS WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPAL GUIDELINES IN EFFECT ON THIS DATE: