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Home My WebLink AboutCOLT S12341 Onsite File Colt #512341 Engineer's Soils Report Colt Subdivision Proposed Subdivision of T12N, R3W, Sec 33, Lot 195 S12341 Municipality of Anchorage Prepared for: Spinell Homes 1900 W. Northern Lights Blvd, Ste. 200 Anchorage, AK 99517 Prepared By: Pannone Engineering Services, LLC P.O.B. 100217 Anchorage, AK 99510 Submitted By: ■ i ♦`- ■ Steven R. Pannone, P.E. Principal, Civil Engineer July 19, 2017 Colt Subdivision Proposed Subdivision of T12N, R3W, Sec 33, Lot 195 Engineering Report Project Description This soils report is to identify the suitability of the soils on the lot being subdivided for an on-site septic system. This subdivision is part of T12N, R3W, Sec 33, Lot 195. This report will detail the soils encountered during the soils investigation, existing topography, impact to surrounding wells and septic system and the suitability of the soils encountered for the use of an on-site wastewater disposal system and water supply system. The two (2) proposed lots will be 1.06 acres in size. The lots are undeveloped, with the exception of a crib, likely the crib permitted and installed on lot 195 in 1970. Soils Investigation Pannone Engineering Services performed a soils investigation on March 3, 2017, in the area that the subdivided lots will be located. The test pits were excavated by the Pomraning Construction and were excavated to the maximum extent of the excavator. The test pits revealed a variety of soils. We encountered in Test Hole one (TH-1) a layer of organics to a depth of one foot (1.0'), underlain with fine sand and gravel with silt to a depth of fourteen feet (14.0'). The layer of sand and gravel was found to have a percolation rate of 5.2 minutes per inch. Based on the percolation rate and the appearance of the soil an application rate of 0.8 gallons per day/ square foot may be used as an application rate. We did not encounter bedrock or impermeable soils in the Test Hole One (TH-1). Permafrost was not encountered in the test pit nor is it suspected in this area. Groundwater was not encountered to a depth of fourteen feet (14.0') during excavation or during the May high groundwater monitoring period. We encountered in Test Hole two (TH-2) a layer of organics to a depth of one foot (1.0'), underlain with fine silty sand with some gravel to a depth of fourteen feet (14.0'). The layer of fine silty sand and gravel was found to have a percolation rate of 8.0 minutes per inch. Based on the percolation rate and the appearance of the soil an application rate of 0.8 gallon per day/ square foot may be used as an application rate. We did not encounter bedrock or impermeable soils in the Test Hole Two (TH-2). Permafrost was not encountered in the test pit nor is it suspected in this area. Groundwater was not Colt Subdivision Proposed Subdivision of T12N, R3W, Sec 33, Lot 195 encountered to a depth of fourteen feet (14.0') during excavation or during the May high groundwater monitoring period. Topography The proposed Colt Subdivision is located on the lower portion of Rabbit Creek Road and is surrounded by developed lots. The slope is generally from the northeast to the southwest. The subject area slopes at approximately 5%with a slope of about 20%-25%just downhill of the lot line and a slope of about 10% below. The area surrounding the test holes and the septic reserve areas slopes at about 5%. Existing water and wastewater systems The proposed subdivision is located at the intersection of Rabbit Creek Road and Loc Loman Lane, in Anchorage. There is an existing crib that was installed in 1970 and is currently being used as an RV dump station. The lot also has a well that was installed in 1965. The current status of the well is unknown. The existing water supply systems on all the surrounding lots are private wells and have a 100 foot protective radius around them (i.e. a new wastewater disposal system may not be located less than 100 feet from these private water wells.) Water Availability This subdivision will be located in a valley on the lower slopes of the surrounding terrain where water is readily available. The surrounding wells are typically between 100 and 200 feet deep. The static water levels range between 0 and 40 feet deep. There is an existing undocumented well on the existing homestead. The existing well flow data that was available showed that the wells with record data could produce approximately at least 2 gallons per minute. Based on the record research and field data we collected,there appears to be adequate water available for the proposed subdivision without affecting the surrounding wells. The well will be approximately 200 feet deep or less and will likely produce at least 2 gallons a minute. Installing these wells will not affect the production of water wells on the surrounding property. Legal Description Well Depth Static Water Level Production T12N, R3W, Sec 33, Lot 188 E2 310 55 5 gpm T12N, R3W, Sec 33, Lot 194 190 63 5 gpm T12N, R3W, Sec 33, Lot 196 E2 133 46 2 gpm Surface water There are no wetlands or surface water within 100' of this subdivision. Colt Subdivision Proposed Subdivision of T12N, R3W, Sec 33, Lot 195 Engineering Criteria The soils in this area are typically organics underlain by silty sand and gravel. PES conducted a percolation test on the proposed lots and found percolation rates as shown above, and on the soils logs. The soils encountered in this area are generally well percolating soils (around 4-8 mpi). An application rate of 0.8 gpd/sf should be used for the design of a wastewater disposal system on the proposed lots as shown on the soils logs and in this report. Groundwater was not encountered on this subdivision. Site Information For a subdivision, a site plan stamped by an engineer must show specific areas for the septic system based on the observed percolation rate and Title 15.65.180, Table 2. These areas must meet all set back requirements of Title 15.65. According to Table 2, and area of 10,000 sf must be shown for areas with a percolation rate of 1-5 MPI, an area of 12,000 sf must be shown for areas with a percolation rate of 5-12 MPI, and an area of 14,000 sf must be shown for areas with a percolation rate of 12-24 MPI. The attached site plan shows the reserve areas per these requirements. The Municipality of Anchorage (Moa) Regulations (15.65) govern for single-family homes. These regulations require a minimum of four (4) feet vertical separation between the bottom of a soil absorption system and ground water for a conventional wastewater disposal system, six feet (6') to bedrock or other impermeable layers (tight silts and clays with a percolation rate greater than 120 minutes per inch) and must be located greater than 100 feet horizontally from any surface water (Creeks and ponds). Additionally, the accepting soils must have a percolation rate of less than 120 minutes per inch. A lot must have room for a primary and reserve soil absorption system. Based on the existing topography, soils investigations conducted to date and record research of surrounding lots, the proposed lots, with the exception of lots 7-10, have in excess of the required contiguous area suitable for an initial and replacement for conventional wastewater disposal systems. II 1 1 II A88W2 188 E2 41 II \ �p�M�M 11 .....8 187 ` �/ 11 4\ W 189A ii 3 WELL(E)J 1 / 1 \ \ f I M 1,y1 I..�� J U_ I " WELL(E) �\w � \ / Wsti \ \ / 64-/St No f RABBIT CRE ROAD �t 33' BLM ROADWAY /� r 35'DEll CATED TO ROADWAY' EASEMENT I 4)"....--------..„i, 1 1 i WELL (P) M "' WELL (P) LOT 2 \ ,i CONTOUR INTERVAL: 2' / WELL (E) .4 \ / I DECOMMISSION PER CODE 3o I 'EXISTING CRIB /� 196 E2 Z o • ABANDON PER CODE 1 go s / z rr _____---m--_____ _,Q 12,000 S.F. • , K' 'N� 8 o RESERVE AREA a 194 / J 1iit TH-2 L \ N � 12,000 S.F. r o/ EP1Ic AREAE) RESERVE AREA i. \1111 I I \ i .._ oW , "�5 .0.- , 3 714: �M ��TH-1 �I �MM 1 vnc A (E) \ \ WELL(E)J yi, ';%.4___I L� —_-GO..\ 'if —72 • •1O'TELEPHONE EASEMENT . — \� /�`/ / TOP OF 25% SLOPE ` �/ w�W�v+ l I M�M-----M 3 I WELL(E) /�/ ,y\ \ WELL(E) f \ (SHORT �/ W SQUARED \�� /�/ opo \�� Ns, �A 11,-_____w___—�+ l�W �o 216„ (E)] ��; 217 ,� \ >v \'p /� www NOTES: LLC �..-,��.\� Dote SOILS REPORT PANNONE ENG SVC, OF At. ‘‘l 7/21/2017 P.O. BOX 100217 ANCHORAGE, AK 99510 ..67:s .' 0 �'SP' 4,..•.1-,710� Scale PHONE (907) 272-8218 FAX (907) 272-8211 ...To.. , 0/ 1"=100' COLT SUBDIVISION %::'�j`�' • a P.I.D. NO � ,• xxx-xxx-xx SUBDIVISION OF T12N, R3W, Sec 33, LOT .te'ver R. "onnorae 5 PERMIT NO. SPINELL HOMES 0 /i.. CE 8149 ...cam,/ S12341 RABBIT CREEK ROAD +vcTgin. ••,;<:,§....1": Sheet PLAN ANCHORAGE, AK ll\� ROF{SS �~ 1 OF 3 SOILS LOG - PERCOLATION TEST TEST HOLE 1 SLOPE ' i I • SITE PLAN I OR ORGANICS �i I ; L`J LOT 2 3 L k 2 A • 3 / \l /- I I I / I w v� I 4 . w.-----14...7. �� 5 \ .M\�\ I \ J .116 TH TH-2 I 7 SM/ FINE SAND GM WITH GRAVEL 8 AND SILT e k`-w-� 9 / :� Cc:-1 �10 IIA �� TH-1 I 11 `r .A 12 / ! \ F E 3 i F 13 WAS GROUND WATER SLOPE 14BOH ENCOUNTERED? N 15 IF YES,AT WHAT TH DEPTH? -DRY X 16 17 DEPTH TO WATER AFTER MONITORING? -DRY 18 DATE: 3/10/17 19 DEPTH TO WATER AFTER CLOCK WATER MONITORING? DRY READING DATE TIME NET TIME LEVEL NET DROP READING DATE: 5/22/17 1 7/19/17 7:56 -- 4.22 DATE PERFORMED: 3/3/17 --- 2 8:06 10 MIN 6.65 2.43 3 8:06 --- 4.22 --- 4 8:16 10 MIN 6.43 2.21 5 8:16 -- 4.22 -- 6 8:26 10 MIN 6.20 1.98 7 8:26 --- 4.22 -- 8 8:36 10 MIN 6.15 1.93 PEROLATION RATE 5.2(min/inch)PERC HOLE DIAMETER 6 inches TEST RUN BETWEEN 3 FT AND 4 FT COMMENTS:Test hole excavated by POMRANING EXCAVATION. PERFORMED BY: Dan Moran. I CERTIFY THAT THIS TEST WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPAL GUIDLINES IN EFFECT ON THE DATE OF THIS TEST. NOTES: ��vo, Dote PANNONE ENG SVC, LLC OF 44....4k0l7/19/2017 SOILS REPORT P.O. BOX 102954 ANCHORAGE, AK 99510 '��' PHONE (907) 272-8218 FAX (907) 272-8211 -offc0. N.,..,,,-- •...• � Scale COLT SUBDIVISION _ s.'f►''vg, °0/ P.I.D. NO % xxx-XXX-XX SUBDIVISION OF T12N, R3W, Sec 33, LOT 195 /� Steven *F�:•F�onnorae.j PERMIT NO. SPINELL HOMES 6r-�•. CE 8149 .•��7 S12341 RABBIT CREEK ROAD #4k cf• ' ,`�� SOILS LOG ANCHORAGE, AK k%�`S``�� ~ Sheet 3 SOILS LOG - PERCOLATION TEST TEST HOLE 2 SLOPE • 1 I . SITE PLAN J I OR ORGANICS • Tom`^ L`J LOT 2 I I 3 ` I I 1 / 4 rr-----• 5 M . 6 X me , I I 6 \ l TH TH-2 cp. 7 FINE SILTY 1 SM! SAND WITH 8 GM SOME GRAVEL 1 r `KL W� 9 CD 1T ,.M�M_1\ -TH-1 I 10 /4' __c,,,-, . 4,, 11 1._„ 12 / 7 \ F 13 WAS GROUND WATER SLOPE 14 ENCOUNTERED? N BOH 15 IF YES,AT WHAT TH DEPTH? -DRY X 16 17 DEPTH TO WATER AFTER MONITORING? -DRY 18 DATE: 3/10/17 19 DEPTH TO WATER AFTER CLOCK WATER MONITORING? DRY READING DATE TIME NET TIME LEVEL NET DROP READING DATE: 5/22/17 1 3/3/17 2:10 DATE PERFORMED: 3/3/17 6.08 --- 2 2:20 10 MIN 7.50 1.42 3 2:20 --- 6.08 --- 4 2:30 10 MIN 7.39 1.31 5 2:30 --- 6.08 --- 6 2:40 10 MIN 7.33 1.25 PEROLATION RATE 8.0(min/inch)PERC HOLE DIAMETER 6 inches TEST RUN BETWEEN 3 FT AND 4 FT COMMENTS:Test hole excavated by POMRANING EXCAVATION. PERFORMED BY: Dan Moran. I CERTIFY THAT THIS TEST WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPAL GUIDLINES IN EFFECT ON THE DATE OF THIS TEST. NOTES: ��..��x\ Dote PANNONE ENG SVC, LLC — OF A�til 7,,9i2o, SOILS REPORT P.O. BOX 102954 ANCHORAGE, A 99510 ..i....-- �� qs k0 PHONE (907) 272-8218 FAX (907) 272-8211 7 ico.• �4,,. . .. , Scale AO*: ' • )� *0/ NTS •..• . ••• Ns ... � P.I.D. NO COLT SUBDIVISION �� xxx-xxx-xx SUBDIVISION OF T12N, R3W, Sec 33, LOT-i•' . � Steven -. -onnone pERMIT N0. SPINELL HOMES /�•V•. CE 8149 .•�i S12341 RABBIT CREEK ROAD .. • SOILS LOG ANCHORAGE, AK ,l \��`�=�� Sheet 3eOF 3