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Home My WebLink AboutLANDING ZONE S12563Onsite File Landing Zone #S12563 Engineer's Soils Report Landing Zone Subdivision, Lots 1-2 Proposed Subdivision of Drake Subdivision, Block 4, Lot 6 S12563 Municipality of Anchorage Prepared for: Spinell Homes, Inc. 1900 W. Northern Lights Boulevard, #200 Anchorage, AK 99517 Prepared By: Pannone Engineering Services, LLC P.O.B. 100217 Anchorage, AK 99510 Submitted By: Steven R. Pannone, P.E. Principal, Civil Engineer September 8, 2020 Landing Zone Subdivision, Lots 1-2 Proposed Subdivision of Drake, Block 4, Lot 6 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 Drake Subdivision, Block 4, Lot 6. 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 each be approximately 1.0 —1.2 acre in size. The lots are currently undeveloped. A permit was issued for the installation of a well and septic system on the eastern half of Drake, Block 4, Lot 6, which will become Landing Zone, Lot 2. See OSP191340. Soils Investigation Pannone Engineering Services performed a soils investigation on June 21, 2019 and February 12, 2020, in the area that the subdivided lots will be located. The test pits were excavated by the owner, and Pomraning Construction and were excavated to the maximum extent of the excavator. The test pits revealed a limited 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 silty gravel and sand to a depth of four feet (4.0'). The layer of silty gravel and sand was found to have a percolation rate of 73 minutes per inch. Finally under the layer of silty gravel and sand, from a depth of 4.0 feet to a depth of 8.0 feet was a layer of vary silty gravel. Based on the percolation rate and the appearance of the soil an application rate of 1 gallon per day/ square foot may be used as an application rate with a disposal field based on Category III treatment. 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 encountered at a depth of three point five feet (35) during excavation and a two feet (2.0') after the 7 -day monitoring period and at high ground water monitoring in October. We encountered in Test Hole two (TH-2) a layer of organics to a depth of four and one half feet (45), underlain with silty gravel and sand to a depth of eight feet (8.0'). The layer of sand and gravel was found to have a percolation rate of 37 minutes per inch. Based on the percolation rate and the appearance of the soil an application rate of 2.0 gallons per day/ square foot may be used with Cat III treatment. Landing Zone Subdivision, Lots 1-2 Proposed Subdivision of Drake, Block 4, Lot 6 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 encountered at a depth of six feet (6.0') during excavation and at three feet (3.0') after the 7 - day monitoring period and at high ground water monitoring in October. We encountered in Test Hole three (TH-3) a layer of organics to a depth of one foot (1.0'), underlain with well graded sand to a depth of seven feet (7.0'). The layer of sand was found to have a percolation rate of 1 minutes per inch. Finally under the layer of sand, from a depth of 7.0 feet to a depth of 10.0 feet was a layer of silty sand and gravel. Based on the percolation rate and the appearance of the soil an application rate of 1.2 gallon per day/ square foot may be used as an application rate with a conventional system. The conventional system however, should be placed on the upslope area along the eastern lot line, and not in the lower basin toward the center of the lot. The upslope area of the lot slopes up to 40%, and therefore the steep slope section of the code will apply to a disposal field located in this area. We did not encounter bedrock or impermeable soils in the Test Hole three (TH-3). Permafrost was not encountered in the test pit nor is it suspected in this area. Groundwater was encountered at a depth of nine feet (9.0') during excavation and at nine feet (9.0') after the 7 - day monitoring period and at a depth of eight feet (8.0') during high ground water monitoring in May. Topography The proposed Subdivision is located on lower -hillside near Huffman Road at the intersection of Flyway Avenue and Gander Street and is surrounded by developed lots. The slope is generally from the east to the west. The subject area slopes at approximately 2% with no steep slopes in the vicinity. There is a small hill to the northeast with a slope of approximately 20% in the northeastern most corner of proposed lot 2. Existing water and wastewater systems The proposed subdivision is located at the intersection of Flyway Avenue and Gander Street, in Anchorage. The existing residential water supply systems on all the surrounding lots to the west, north, and east 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.) The area to the south (Kempton Hills Subdivision) is served by AWWU water and sewer. Landing Zone Subdivision, Lots 1-2 Proposed Subdivision of Drake, Block 4, Lot 6 Water Availability This subdivision will be located on the lower Anchorage hillside where water is readily available. The surrounding wells are typically between 50 and 150 feet deep. The static water levels range between 0 and 43 feet deep. The existing well flow data that was available showed that the wells with record data could produce approximately at least 15 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 150 feet deep or less and will likely produce at least 15 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 Nitrates MG/L Drake, Block 1, Lot 6 55 0 15 gpm 12/28/94 2.64 11/18/88 1.3 Drake, Block 4, Lot 8B 152 34 15 gpm Unk Drake, Block 4, Lot 8 152 43 20 gpm 11/18/12 5.15 Drake, Block 3, Lot 1 82 24 10 gpm 3/29/19 6.36 Drake, Block 4, Lot 7 128 40 15 gpm Unk Drake, Block 4, Lot 4 74 13 4.4+ 10/4/13 2.81 Surface water There are no wetlands or surface water within 100' of this subdivision. There are class 'C' wetlands located just to the west, with no apparent surface water. 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 medium -slow percolating soils (around 30 mpi or slower). An application rate of 1.2 gpd/sf should be used for the design of a wastewater disposal system on the proposed lot 2 with the use of the steep slope section of the code, and an application rate of 2 gpd/sf may be used for the design of a wastewater disposal system on the proposed lot 1 with use of Cat III treatment as shown on the soils logs and in this report. Groundwater was encountered on this subdivision at 8 feet on lot 2 and at 3 feet on lot 1. Landing Zone Subdivision, Lots 1-2 Proposed Subdivision of Drake, Block 4, Lot 6 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. *4' CONTOURS o �F 3 3 ( `-WELL (E) I 1WE11 (E) � vaJi 2 _\ X 3 / SEPTIC AREA (E) 4 I iii �• \ ' I � _ t0' un ITY EASEMENT 1 1 • ..a... —_ _ 10. UTiutt EASEMENT -/ _. �TH-2 I TH-3 ! J CLASS 'C' WETLANDS 16,000 S.F. I I SEPTIC RESERVE ; ( AREA i \` \ • • �"+� ' 10,000 S.F. LJs l SEPTIC RESERVE AREA 'N. (`191.3 _ 271'8 r TO SEPTIC AREA (E) I TO SEPTIC AREA (E) l • /p `- WELL (E)� / .. i .... I • • / S 'WELL (P) �� I j' FLYWAY AVENUE • \ ADJACENT LOTS TO THE SOUTH ARE SERVED BY AWWU WATER AND SEWER 24 25 42 ( 43 II I � I NOTES: ��T A� �T �T LLC PAI�1NONE ENG SVC, LLI. P.O. BOX 100217 ANCHORAGE, AK 99510 PHONE (907) 272-8218 FAX (907) 272-8211 ..,�►~~,°`late QF A��,�1� .r '� ' ' ' ' ' '9cS' l� * . *#I % """' Steven R. Pannone �/ �r��'F. 9/2/2020 SUBDIVISION REPORT Scale 1"=100' LANDING ZONE SUBDIVISION A SUBDIVISION OF DRAKE, BLOCK 4, LOT 6 P.I.D. NO 417-462-04 PERMIT N0. SPINELL HOMES INC. CE 8149 , <�®® csTF`�•: S-12563 Street 1 OF 5 100SCALE PLAN FLYWAY AVENUE ANCHORAGE, AK ,l�QFESSIONP4 10® �.yo^` *4'CONTOURS 10' UTILITY EASEMENT 10' UTILITY EASEMENT —3 TH-2 TH < 16,000 S.F. SEPTIC RESERVE AREA 10,000 S.F. SEPTIC RESERVE,\ AREA 706 7 M /00 /01 1 TH-1 L T AA r ZD I-- uj LLJ IWELL (P) WELL (P) FLYWAY AVENUE' NOTES: Date PAMONE ENG SVC, Li -c SUBDIVISION REPORT 91� �t.4'�Ak 9/2/2020 P.O. BOX 100217 ANCHORAGE, AK 99510 - Scale PHONE (907) 272-8218 FAX (907) 272-8211 co - 1"=50' P.I.D. NO LANDING ZONE SUBDIVISION 417-462-04 A SUBDIVISION OF DRAKE, BLOCK 4, LOT 6 S* . teve . n . R. . a o* n' e* llRMIl NO. SPINELL HOMES INC. CE 8149 S-12563 FLYWAY AVENUE PLAN c� Sheet ANCHORAGE,AK 2 OF 5 READING SOILS LOG - PERCOLATION TEST CLOCK TIME NET TIME TEST HOLE 1 NETpROP 1 6/21/18 ORGANICS SLOPE E --- OR 5:00 30 MIN 1 0.75 s � 2 TIGHT SILTY --- 10,000 S.F. 7 GM/SM SAND AND SEPTIC RESERVE 3 GRAVEL 7.45 AREA 7� 5:30 --- 70�' 4— s 6:00 5 SILTY GRAVEL 7.42 0.41 WITH WATER \ 6 GM FREELY FLOWING X TH 70, 7 THROUGH I( TH —1 8 1 / BOH 9 M --.-. ✓ 10 11 12 13 WAS GROUND WATER SLOPE 14 ENCOUNTERED? Y 15 IF YES, AT WHAT TH 16 DEPTH? -3.5' x 17 DEPTH TO WATER AFTER MONITORING? -2.0' 18 DATE: 6/28/18 19 DEPTH TO WATER AFTER MONITORING? -5.0' DATE PERFORMED: 6!21!18 DATE: 7/26/19 DEPTH TO WATER AFTER MONITORING? -2.0' DATE: 10/15/19 PEROLATION RATE 73 (min/inch) PERC HOLE DIAMETER 6 inches TEST RUN BETWEEN 1.5 FT AND 2.5 FT COMMENTS: Test hole excavated by LOT OWNER 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: r -+ PAMONE L'il�llJ SVC, C, LLrI. P.O. BOX 102954 ANCHORAGE, AK 99510 PHONE (907) 272-8218 FAX (907) 272-8211 : "`OF AC �l>1 '� ' ' ' ' ' '9S �e ' .4� M *��/ % ' ""' J Steven .R. Pannone / Date 9/2/2020 SUBDIVISION REPORT Scale NTS LANDING ZONE SUBDIVISION A SUBDIVISION OF DRAKE, BLOCK 4, LOT 6 P.I.D. NO 017-462-04 PERMIT N0. SPINELL HOMES INC. FLYWAY AVENUE ��'�c. CE 8149 � s 2t`�d ``�'' li1°ROFESSIONP yr S-12563 sheet SOILS LOG ANCHORAGE, AK �1®� 3 OF 5 READING DATE CLOCK TIME NET TIME WATER LEVEL READING NETpROP 1 6/21/18 4:30 --- 7.01 --- 2 5:00 30 MIN 7.76 0.75 s 5:00 --- 7.01 --- a 5:30 30 MIN 7.45 0.44 s 5:30 --- 7.01 --- s 6:00 30 MIN 7.42 0.41 TEST HOLE 2 SOILS LOG - PERCOLATION TEST SLOPE SITE PLAN 1 T 2 OR/PT ORGANICS AND 1 0' UTIL PEAT 10UTILI 3 TH-2 4 5 / 6 GM/SM SILTY SAND X RVE AND GRAVEL TH 7 $ BOH / 10,0 9 SEPTIC A 10 11 12 13 WAS GROUNDWATER SLOPE 14 ENCOUNTERED? Y 15 IF YES, AT WHAT TH 16 DEPTH? -6.0' x 17 DEPTH TO WATER AFTER MONITORING? -3.0' 18 DATE: 6/28/18 19 DEPTH TO WATER AFTER CLOCK WATER MONITORING? -3.0' TIME DATE PERFORMED: 6/21/18 DATE: 10(15119 2 5:45 30 MIN 7.58 0.87 s 5:45 --- 6.71 --- a 6:15 PEROLATION RATE 37 (min/inch) PERC HOLE DIAMETER 6 inches TEST RUN BETWEEN 4.5 FT AND 5.5 FT COMMENTS: Test hole excavated by LOT OWNER 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: PAMONE ENG SVC LLC ®`® \e Date SUBDIVISION REPORT O. AC A, k 9/2/2020 P.O. BOX 102954 ANCHORAGE, AK 99510 '� S PHONE (907) 272-8218 FAX (907) 272=8211 /®GjP �.7 Scare TH NTS LANDING ZONE SUBDIVISION % .I.D04 . N A SUBDIVISION OF DRAKE, BLOCK 4, LOT 6 Steven 'R. 'Pon one /PERMIT N4 SPINELL HOMES INC. r� �'� . CE 8149c�rs�°° O. S-12563 FLYWAY AVENUE111 SOILS LOG ANCHORAGE, AK �ll�®Ot�FPROFESSI4N� Sheet 5 t, ®•o�- READING DATE NET TIME LEVEL READING NET DROP � 6!21!18 5:15 --- 6.71 --- 30 MIN 7.55 0.84 s 6:15 --- 6.71 --- s 6:45 30 MIN 7.53 0.82 TEST HOLE 3 OR I ORGANICS 1 2 3 4 SW SAND 5 6 7 8 GM/SM SILTY SAND 9 AND GRAVEL 10 BOH 11 12 13 14 15 16 17 18 19 DATE PERFORMED: 2/12/2020 SOILS LOG - PERCOLATION TEST SLOPE x TH r 10' UTILITY EAJMfft i 10' UTILITY EASEMENT 0� 1� WAS GROUND WATER ENCOUNTERED? Y IF YES, AT WHAT DEPTH? -9.0' DEPTH TO WATER AFTER MONITORING? -9.0' DATE: 2/25/2020 DEPTH TO WATER AFTER MONITORING? -8.0' Date: 5/11/2020 10,000 S.F. SEPTIC RESERVE AREA ®ems TH x READING DATE CLOCK NET TIME WATERTIME LEVEL READING NETDROP 1 2/12/2020 11:45 --- 4.88 -- 2 11:50:48 5.8 MIN 10.88 6.00 3 11:51 --- 4.88 --- 4 11:57:06 6.1 MIN 10.88 6.00 5 11:58 --- 4.88 --- 5 12:04:08 6.1 MIN 10.88 6.00 PEROLATION RATE 1 (min/inch) PERC HOLE DIAMETER 6 inches TEST RUN BETWEEN 2.5 FT AND 3.5 FT COMMENTS: Test hole excavated by POMRAINING 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: ��T �T ®-+"`a Date SUBDIVISION REPORT PANN®NE ENG SVC, LLC .^ OF A14 l_,q` 9/2/2020 P.O. BOX 102954 ANCHORAGE, AK 99510 '�� 'qc' 11 PHONE (907) 272-8218 FAX (907) 272-8211 s CrJv Scale 4 11I R�o NTS LANDING ZONE SUBDIVISION % G , PERMIT 462 04 N0. A SUBDIVISION OF DRAKE, BLOCK 4, LOT 6 "S't'e've'n 'R. •Pannone / SPINELL HOMES INC. t♦� �F . CE 8149 - ERMIT3 FLYWAY AVENUE i�cs�fip�v`�r S-1256Sheet SOILS LOG ANCHORAGE, AK �l ®PROFESSo 5 OF 5