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Home My WebLink AboutOBERG S12441 Onsite File Oberg Ltl & 2 #512441 OBERG L A-2 Soils Report Engineer's Soils Report OBERG L A-2 S-12441 Municipality of Anchorage Prepared for: Diane Sullivan PO BOX 670272 Chugiak, AK 99567 Prepared By: Pannone Engineering Services, LLC P.O. Box 100217 Anchorage, AK 99510 Submitted By: */49la %.* ..i'+ : • .'$leven -. -annO?e CE814y9 •�.;• Steven R. Pannone, P.E. Principal, Civil Engineer 28 November 2018 OBERG L A-2 Soils Report Engineering Report Project Description This soils report is to identify the suitability of the soils on the proposed lots for an on-site septic system on each proposed individual lots within OBERG L A-2.The subject lots are for the proposed subdivision of OBERG L A-2 (adding L A-3 & L A-4).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 lots are both 0.92 acres in size. The proposed subdivided lots are currently undeveloped with the remainder of LA-2 being developed. Soils Investigation Pannone Engineering Services performed a soils investigation In September of 2018 on both lots and conducted water monitoring in October.The test pits were excavated by the homeowner and were excavated to the maximum extent of the excavator or until refusal. The test pits revealed a fairly homogenous cross-section of soils as shown on the attached Soils Logs for each of the proposed subdivision lots. Topography The lot is characterized by generally level topography as a whole. (see attached subdivision site plan). Existing water and wastewater systems The proposed lots are currently undeveloped with the remainder of LA-2 having been developed. There are developed lots along the south and east of the lots with the land to the west being occupied by a public park. The existing water supply systems 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 documented wells are far enough back on the lot that their protective well radiuses do not affect the proposed subdivision lots. Surface water There are no major bodies of surface water within 200 feet of the proposed septic areas. There are ephemeral drainage ditches along the existing road (Oberg Road). Engineering Criteria The soils in this area are typically Hydrologic Soils Group A which contains organics generally underlain by gravel and sand. PES conducted four percolation tests on the proposed lots and found a percolation rate varying from three minute per inch (3.0mpi)to eight minutes per inch (8.0mpi). The soil composition and percolation rate confirms the soil classification of HSG A. Based upon the soil test results there are several options for systems that could be installed on all of the lots. There are no steep areas within the respective reserve areas. The table below has the test hole depths, percolation rates and depth to ground water on each perspective lot in the subdivision. OBERG L A-2 Soils Report GROUND H2O LOT TH# TH DEPTH PERC RATE LEVEL REQUIRED RES AREA A-3 TH-A-3 15.0 3.2 NO 10000.0 A-4 TH-A-4 16.0 8.0 15.75 12000.0 Site Information 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) 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. Water Availability There is availability for a private water system on the lot. A survey of the well data from the surrounding lots is provided on the table below. Data shows ample water availability in the lots surrounding the above referenced lot. Existing lots to the north and west are served by either a community water system or private well. Legal Well Well Production Static Water Nitrates Date Description Depth Level OBERG L A-2 225' 25gpm 189' OBERG L A-1 242' 100gpm 192' LAMPERT EST 152' 15gpm 154' B1 L6 LAMPERT EST 249' 50gpm 159' B1 L4 CLEARY L2 221' 3.3gpm 181' 3.52mg/L 05/24/2009 BEAM L2 198' 3+gpm 176' Satisfactory 05/30/1985 • _, --(711 -3o�--13 = t I co 4 mI mmnm '9 rTl F3-og O�rriy Ap cmn� _ r gi A-0 O 0 p rp - ( .� 0Ci pmt = -iz Z Wmoo v' Z * O D m rm- Z r m O m MA -i bDr O Z 9 C m N', I , ,.( c 1 1 ( ,' = .� ! * `+ 1 _ ** * ��. a\ 1 P. • j 4 m I\ m q 1,1--._....., I m N U - v ,........,.....f.'s...;::....--..-1.11..-r-i.,..••-r T....urn...rm.-l Ammo s.Is....al a... A.;pM� M a ' \1 ', ;--1 4 / j/ ,„_-. /11........,_ \ D �\L p l. 50�� 3 _ I //j/ __ --' _1 1 4 4--.— .—.—.—:,z.:-.— . .—.— —. .—.—I 29, /I \N N,. ._ _ _ _ _ . _,„.._______,/- , . , 4. . ________ ________:_______ 1.3 \w —mow / 00 '��'� � ` - H , .., . • �.-•i ' i I 8 ' / Wla 1 — H I F/ N r /'z• NOTES: PANNONE ENG SVC LLC REVISIONS DATE FOR MOA REVIEW ONLY P.O. 80X 102954 ANCHORAGE, AK 99510 REV:11/28/2018 10/02/2018 PHONE (907) 272-8218 FAX (907) 272-8211 ' SCALE OBERG L-A2 -* 4em. .* 1' = 100' — P.I.D. NO DRAWN JRL SUBDIVISION: OBERG L-A3, L-A4 slev«i�R4 anrio�e - 051-102-87 DIANE SULLIVAN CE 8149/ PERMITNO. . 41 SITE PLAN PO BOX 670272 °�y�qi -SHEET CHUGIAK, AK 99567 1 OF 2 NOTES & SPECIAL PROVISIONS: TEST HOLE L-A-4 SOILS LOG co I` 1. SCOPE AND SPECIFICOR TOPSOIL 5 001 ; N 1 ORANGE v WATER RATE N (V p Tr 1.1. ALL CONSTRUCTION SHALL BE INSTALLED AS SPECIFIED IN THE MOST CURRENT EDITION OF THE SILTY/SAND READING DATE NET TIME LEVEL NET DROP NM) N z- Z N p MUNICIPALITY OF ANCHORAGE STANDARD SPECIFICATIONS(MASS)FOR COMPONENT PARTS AND 2 READING ( o W Z I .- I MATERIALS USED IN CONSTRUCTION OF ON-SITE WASTEWAER DIPOSAL SYSTEMS AND AND IN I 12SEP18 5.900' W " o- 5V) W" ACCORDANCE WITH AMC 15.65 AND 15.55. 3 2 10 MaN 6783" 2.883' 3.5 c O N C. w0. In 1.2 SCOPE OF WORK: SEPTIC ACCEPTABILITY TESTS FOR SUBDIVISION 4- 3 5900" 1.3. GROUNDWATER WAS NOT ENCOUNTERED TO A DEPTH OF 18 FEET BELOW EXISTING GRADE AS to EVIDENCED BY THE SOIL TEST HOLE. IF AN APPARENT WATER TABLE IS OBSERVED IN ANY OF THE 5 4 10 MIN 8.633' 2.733' 3.7 EXCAVATIONS LESS THAN 18 FEET BELOW EXISTING GRADE NOTIFY THE ENGINEER IMMEDIATELY. 5 5.900' _ In N 1.4. STRUCTURES DEPICTED ON THE SITE PLAN ARE BASED UPON ONE OF THE FOLLOWING:CONCEPTUAL 6- 6 10 MIN 6.590' 2.690' 3.7 o coi PLOT PLAN DEVELOPED BY OWNER;A PLOT PLAN DEVELOPED BY RLS;OR A SURVEY AS-BUILT. 7 SM/GM n \ 2. CONSTRUCTION SPECIFICATIONS: SILTY SAND w 8- & GRAVEL WAS GROUND WATER SOIL TEST RESULTS/ANALYSIS 2.1. ALL EXCAVATION DEPTHS ARE ADVISORY.THEY ARE TO BE VERIFIED AND MAY BE MODIFIED BY THE ENCOUNTERED? N • PERCOLATION RATE 3.2(minfinch) Y.51 ENGINEER IF ACTUAL FIELD CONDITIONS VARY FROM THOSE USED TO PREPARE THE DESIGN 9- (Hydrologic Soils Group: HSG A) ec 2.2. EXCAVATE THE DRAIN FIELD.BOTTOM OF EXCAVATION SHALL BE LEVEL AND SCARIFIED.RECORD IF YES. AT WHAT • PERC HOLE DIAMETER 6" ELEVATIONS AT BEGINNING.MIDDLE AND END OF TRENCH BOTTOM. CONSTRUCTION EQUIPMENT 1O- DEPTH? •-NA-' • TEST RUN BETWEEN FT AND 6 FT. SHALL NOT OPERATE ON THE FLOOR OF THE EXCAVATION. ANY MATERIAL COMPACTED BY THE • TEST RUN FOR OVER AN HOUR, .• OPERATION OF THE CONSTRUCTION EQUIPMENT SHALL BE REMOVED AND REPLACED WITH 11 DEPTH TO WATER AFTER LAST THREE READINGS PROVIDED. UNCOMPACTED MATERIAL. 12 MONITORING? - DRY - L� • 5 0 ••�+ 2.3. PLACE THE SEWER ROCK TO THE SPECIFIED DEPTHS.DO NOT CONTAMINATE SEWER ROCK WITH DATE: O1OCT2018 • A, NATIVE MATERIAL OR SPOILS FROM EXCAVATION.LEVEL ROCK SURFACE TO i1"PRIOR TO INSTALLING 13- ,{{,�• ti8'�' THE PERFORATED PIPE. Q -� 2.4. ALL PIPE SHALL BE PVC CONFORMING TO ASTM D3034 OR ENGINEER APPROVED EQUAL.MINIMUM 14 COMMENTS:Test hole excavated by HOMEOWNER. 't *•• •o SOIL COVER SHALL BE 3 FEET OVER THE PIPE AND 4 FEET OVER THE SEPTIC TANK.ONE INCH OF S%••, • �, INSULATION MAY BE SUBSTITUTED FOR 1 FOOT OF SOIL COVER. 15 A$4 2.5. ALL INSULATION SHALL BE 2"THICK DOW HI-40 INSULBOARD OR ENGINEER APPROVED EQUAL. BOH PERFORMED BY:Joseph Lawendowski.I CERTIFY THAT THIS TEST •CENTER INSULBOARD WIDTH OVER SEPTIC TANK OR LINES. - WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPAL - ' 2.6. GEOTEXTILE SHALL BE MIRAFI 1405 OR ENGINEER APPROVED EQUAL.LAP ALL JOINTS 2 FEET GUIDLINES IN EFFECT ON THE DATE OF THIS TEST. MINIMUM. - 2.7. COVER THE DISTRIBUTION PIPE WITH A MINIMUM OF 2'OF SEWER ROCK AND COVER WITH GEOTEXTILE BEFORE PLACING INSULATION AND BACKFILL. - c} 2.8. MATERIAL USED AS FILL SHALL BE CLEAN AND FREE OF ORGANICS.TRASH AND CONSTRUCTION Q DEBRIS. DATE PERFORMED: 12SEP18 I 2.9. SLOPE ALL FILL MATERIAL TO DRAIN AT 2%MINIMUM SLOPE AND 3:1 MAXIMUM SLOPE AND IN SUCH 0FlJ CO A MANNER THAT PONDING AT OR NEAR THE DRAIN FIELD DOES NOT OCCUR.THE FILL SHALL BE LEFT (./u1 I AT 6"HIGHER THAN SHOWN TO ALLOW FOR SETTLEMENT.SEED SURFACE AFTER COMPLETING Jrn.. F. INSTALLATION AS PER MOA CODE. TEST HOLE L-A-3 SOILS LOG J•�-- t4 I 2.10. RECORD THE FINISH GROUND ELEVATION OVER THE BEGINNING.MIDDLE AND END OF SYSTEM. n Z CV cs. t45in 2.11. MAINTAIN 5'SEPARATION BETWEEN PERCOLATION HOLE AND THE DRAIN FIELD TRENCH. OR TOPSOIL (��el N I Q 2.12. EXPOSE.MOA CODE IIF NEEDED. LOG DISPOSAL CRIB OR CONCRETE TANK WITH SOIL TO ABANDON LAW WITH 1 SM SILTY o READING DATE NET nME GE WATER ALEERL NET DROP RATE H.4 x < J > O C7 2 READING ( ) v oz J 0 J r Y 3. CONTRACTOR RESPONSIBILITIES: 3- I 12SEP18 5.900" Z Z Q 2 10 MIN 7.358' 1.456' 6.9 W a m Li m '' X 3.1 THE CONTRACTOR(BOTH WELL AND SEPTIC SYSTEM CONTRACTORS)SHALL HAVE ANY WELL LOCATION 4 3 5.900 11". 1 CC O O `1 AND SEPTIC LOCATION STAKED AND ANY LOT LINE AND WELL RADIUS SHOWN ON THE PLAN WITHIN 30 Zo,^ W W FEET OF THE PROPOSED SYSTEM STAKED BY A REGISTERED LAND SURVEYOR BEFORE STARTING THE 5- 4 10 MIN 7.200" 1.300' 7.7 OOCV EE) _ Z Cn Q WORK. 5 5.900 Z^iZ O Z < 0 O 3.2. THE CONTRACTOR IS RESPONSIBLE FOR ALL R.O.W.AND OTHER REQUIRED PERMITS.OTHER THAN 6- xcD THE ATTACHED. 6 '0 MIN 7.150' 1.250' 8.0 (CCD � 0_ (L= 3.3. THE CONTRACTOR SHALL CALL FOR LOCATING OF ALL BURIED UTILITIES. 7 SM/CM w - C.)3.4. THE CONTRACTOR SHALL PROVIDE 24 HOUR NOTICE TO THE ENGINEER PRIOR TO START OF WORK. SILTY SAND fs.oz ALL SURVEYING AND LOCATES SHALL BE IN PLACE PRIOR TO NOTIFYING THE ENGINEER. 8- & GRAVEL WAS GROUND WATER SOIL TEST RESULTS/ANALYSIS °C. > 3.5. THE CONTRACTOR SHALL NOTIFY THE ENGINEER OF ANY DISCREPANCY BETWEEN THE APPROVED ENCOUNTERED? N • PERCOLATION RATE 8.0(minRnch) 0 DRAWINGS AND SITE CONDITIONS/LIMITATIONS POTENTIALLY CAUSING THE NEED TO MODIFY THE 9- (Hydrologic Soils Group: HSG A) CO DESIGN. IF YES. AT WHAT • PERC HOLE DIAMETER 8" D 3.6. AT THE COMPLETION OF THE WORK,THE CONTRACTOR SHALL SUBMIT RED-LINE AS-BUILT DRAWINGS t0- DEPTH? -NA-' • TEST RUN BETWEEN 5 F AND 6 FT. 1./7 TO THE ENGINEER. THE RED-LINES SHALL INCLUDE PIPE LENGTHS,ORIGINAL GROUND ELEVATIONS. • TEST RUN FOR OVER AN HOUR, PIPE ELEVATIONS,AND TANK ELEVATIONS. 1i DEPTH TO WATER AFTER LAST THREE READINGS PROVIDED. 3.7. THE CONTRACTOR SHALL PROVIDE PHOTOGRAPHS OF THE SYSTEM INSTALLATION TO INCLUDE 12 MONITORING? - 15.75' - BOTTOM OF EXCAVATION.TOP OF PIPE WITH CLEAN-OUTS AND MONITOR TUBES INSTALLED. DATE: 01OCT2OI8 INSTALLED TANK AND FINAL GRADING. t3 } J 4. THE CONTRACTOR SHALL SIGN THE FOLLOWING: I CERTIFY THAT ALL WORK WAS PERFORMED IN Z 14 COMMENTS:Test hole excavated byHOMEOWNER. ACCORDANCE WITH THE APPEND PERMIT,AND ANY AND ALL CHANGE ORDERS.AND THAT THE AS-BUILT REDLINES ARE TRUE AND ACCURATE REPRESENTATION OF THE PROJECT AS CONSTRUCTED. 3 C. 15- PERFORMED BY:Joseph Lawendowski.I CERTIFY THAT THIS TEST W CONTRACTOR: BY: 16 WAS PERFORMED IN ACCORDANCE WITH ALL STATE AND MUNICIPAL W 5 W TITLE: DATE: BOH GUIDLINES IN EFFECT ON THE DATE OF THIS TEST. p F_ z Oa ^(f) O [ O O. a DATE PERFORMED: 12SEP18 00 o (I)