HomeMy WebLinkAboutKNIK VIEW ESTATES S12448Onsite File
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Estates
Tract C
April 23, 2019
PO BOX 240773
ANCHORAGE, AK 99524
522-7773
677-7766 (FAX)
FORGECIVIL.COM
MOA Development Services, On -Site Water & Wastewater Program
4700 Elmore Rd
Anchorage, AK 99507
Subject: S12448 - Knik View Estates, Tract C
Septic System Feasibility Study
Dear On -Site Services Engineer:
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BenjaS'chiller
CE 12592�`��.�'
PROFESSI4NR �
A petition has been submitted to subdivide one tract into two properties in the existing Knik View
Estates subdivision. 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 north at grades between 5 and 10%.
There are a few areas that are steeper right at the property boundary at the road, but they are small
areas. The new lot sizes are both over 40,000 SF each, and the attached site plan demonstrates that
there is enough space available to meet separation requirements for the future septic systems.
Test holes were dug in early October of 2018. Two test holes were placed on each property in areas
that seemed appropriate for septic locations. Monitoring tubes were placed in the test holes and
groundwater checked on October 11, over a week after the last hole was excavated. The test holes
were dug down to 15'-18' in most areas. Groundwater was encountered in most of the test holes,
typically around 8-10. Soils were varied significantly in the area, ranging from sandy gravels to
silty sands, with a few small pockets of dense silt.
Percolation benches were constructed between 4-6' below the ground surface in each test hole.
Test Hole 1 on Lot C-1 was perked in two separate layers. The percolation cavity in each bench
was prepared and presoaked in accordance with municipal requirements. Again, results were
varied, with some perk rates falling under 1 min/in., while another was 40 min/in.
A septic system was designed and permitted for the home that is on the future Lot C-1. Using the
slope and perk test information, an area appropriate for septic systems was set aside for Lot C-2.
According to Table 7 of municipal code, Lot C-2 had a test hole that perked at 40 min/in, so 16,000
SF was set aside.
A significant portion of both lots is covered by a power line easement. An encroachment permit
will be necessary for any portion of a septic system that falls within this easement. MEA has issued
a general letter of non -objection allowing this easement to be considered as septic reserve area.
All of the existing lots in the area are served by public water; and both of the new lots have access
to water mains.
Based on our field studies, research, and water monitoring completed to date, it is clear that both
lots of the proposed subdivision are capable of supporting neer onsite septic systems.
Sincerely,
Benjamin Schiller, PE
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MUNICIPALITY OF ANCHORAGE
DEVELOPMENT SERVICES DEPARTMENT
4700 ELMORE ROAD ANCHORAGE, AK 99519-6650
SOILS LOG AND PERCOLATION TEST
LEGAL DESCRIPTION: KNIK VIEW ESTATES LC2
PERFORMEDFOR: TROY DAVIS
DATE: 10/03/18 PROJECT No.:
PARCEL ID#: - TECHNICIAN: J. MILLETTE
DEPTH TEST HOLE I l
(I'ccI)
2
3
4
5
6
7
8
9
1
11
12
13
14
15
16
17
18
19
2
ml
SILTY GRAVEL (GM)
SLOPE
mp:
S T E PLAN
SEE SITE PLAN
COMMENTS:
DATE
READING
WAS GROUND WATER ENCOUNTERED?
NO
DEPTH To
WATER
(INCHES)
NET DROP
(INCHES)
10/11
IF YES @ WHAT DEPTH?
- L
1
16:38
DEPTH OF WATER AFTER MONITORING:
8 0
2
17:08
DATE OF MONITORING:
10/11/18 P
216
u
3
17:09
E
414
HARDPAN
4
17:39
30
BOH
COMMENTS:
DATE
READING
GROSS TIME
(MINUTES)
NET TIME
(MINUTES)
DEPTH To
WATER
(INCHES)
NET DROP
(INCHES)
10/11
TEST HOLE PRESOAKED PRIOR TO TESTING:
1
16:38
4 4
2
17:08
30
616
216
3
17:09
414
4
17:39
30
50
is
5
17:40
44
6
18:10
30
5 -1L2
16
16
PERCOLATION RATE: 40 (MIN/INCH) PERC. HOLE DIA.--§�INCHES)
TEST RUN BETWEEN: 5 FT. and 6 FT.
DePTF-F
(Feel)
1-
2 -
J "
4-
5-
6-
7-
8-
9-
10-
11-
12-
IJ-
14-
15-
16-
17-
18-
19 -
MUNICIPALITY OF ANCHORAGE
DEVELOPMENT SERVICES DEPARTMENT
4700 ELMORE ROAD ANCHORAGE, AK 99519-6650
SOILS LOG AND PERCOLATION TEST
LEGAL DESCRIPTION: KNIK VIEW ESTATES LC2
PERFORMEDFOR: TROY DAVIS
DATE: 10/03/18 PROJECT No.:
PARCEL ID#: - TECHINTICIAN: J. MILLETTE
TEST HOLE 2
FILL & ORGANICS
SANDY SILTY GRAVEL (GM)
neers
SITE PLAN
SEE SITE PLAN p
BOH HARDPAN
COMMENTS:
DATE
WAS GROUND WA'FGR ENCOUNTERED? NO
GROSS TIME
NET TIME
IF YES r WHA"r DEPTH? -
SL
DEPTH OP WATER AF"rER YIONITORING: NONE
(MINUTES)
(INCHES)
(INCHES)
DATE Or NIONI'FORING: 10/ I I / 18
P
1
15:07
E
60
BOH HARDPAN
COMMENTS:
DATE
READING
GROSS TIME
NET TIME
DEPTH To
WATER
NET DROP
(MINUTES)
(MINUTES)
(INCHES)
(INCHES)
10/11
TEST HOLE PRESOAKED PRIOR TO TESTING:
1
15:07
60
2
15:37
30
8 —0
2 � 6
3
15:38
6 16
4
16:08
30
8 10
2 -s
5
16:09
6 16
6
16:39
30
8-1
2 is
PERCOLATION RATE: 15 (MIN/INCH) FERC. HOLE DIA. 6 (INCHES)
TEST RUN BETWEEN: 5 FT. and 6 FT.
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