HomeMy WebLinkAboutBRADLEY S-11382Bradley
5-11382
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ANDERSON ENGINEERING
P.O. BOX 240773
ANCHORAGE, AK 99524
•7773 522-6779 (F
August 2, 2005
Municipality of Anchorage
Building Safety Division
On -Site Water and Wastewater Program
4700 S. Bragaw Street
Anchorage, AK 99507
Attention: Dan Roth
Subject: Proposed Bradley Subdivision, Lots 1 and 2
Septic System Feasibility Study
S-11382
Dear Dan:
Test holes were placed on Lots 1 and 2 of the proposed Bradley Subdivision on June
22, 2005. The purpose of the test holes was to assess the underlying soil conditions
and to determine whether septic systems could be placed on the lots to serve single-
family homes. The test holes were placed to depths of 17.5' utilizing a tracked
backhoe. An experienced soils technician under my supervision was onsite during the
excavation to log the soils encountered and to perform percolation tests to determine
the absorption characteristics of the materials encountered. A monitor tube was placed
in each hole to determine the groundwater elevation over a period of time. No
groundwater was found in any of the holes during excavation and none has been noted
to date.
The surface of the proposed subdivision slopes from southeast to northwest at varying
grades. None of the grades in the subdivision exceeds 15% in the area of the
proposed septic systems and is usually much flatter. The property is currently slightly
treed with both spruce and birch and some areas are thick with underbrush. During the
exploration period the ground was clear and dry.
A total of 3 test holes were placed throughout the 2 lots. Soils encountered were
similar in all the holes with the upper 1.5' composed of organics with some peat and
organic silt. This layer was underlain by poorly graded to well graded gravel with
varying degrees of sand and silt. The majority of the material was found to be clean
and fairly dry. Percolation rates were usually less than 2 minutes per inch. This type
of material is excellent for the treatment and disposal of septic effluent. A tighter siltier
layer was found beneath the poorly graded gravel and was visually classified as GM.
This material percolated slower at a rate of 33 minutes per inch. This lense extended
from between 5.5' to 9' below the surface and continued to the bottom of each test
Proposed Bradley Subdivision
August 2, 2005
Page 2 of 2
hole. As mentioned earlier, no groundwater was found in any of the holes during
excavation and none is expected to accumulate during the ensuing heavy runoff period.
The Municipal ordinance governing septic systems requires either a reserve area on
each lot for septic systems or a minimum of three septic system sites designated on the
final plat. Based on our field exploration it appears a minimum of 14,000 square feet of
reserve area can be found on each lot for septic system development.
Copies of the test hole logs and percolation test along with a Test Hole Location Plan
with the locations for the septic system reserve areas and well locations are attached
for your review.
Sincerely,
Michael E. Anderson, P.E.
Attachments
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PROJECT #: _
PERFORMED FOR:
I"IUNICIPALI I OF ANCHORAGE
DEVELOPMENT SERVICES DEPARTMENT/BUILDING SAFETY DIVISION
ON-SITE WATER AND WASTEWATER PROGRAM
4700 SOUTH BRAGAW ANCHORAGE, AK 99519
SOILS LOG - PERCOLATION TEST
DATE PERFORMED: 6/22/2005
LEGAL DESCRIPTION: 41/2. S1/2. NE1/4, SE1/4, NE1/4
TEST HOLE # 1 SLOPE SITE PLAN
N
See Site Plan
I __K// .I OG/OL
2
3
L Poorly Graded
Gravel GP
5
6
VA
8
GROSS
TIME
Silty Gravel
DEPTH TO
WATER
NET
DROP
WAS GROUNDWATER
9
Dark Gray ENCOUNTERED? NO
1
Damp
10
13.75"
IF YES, WHAT DEPTH?
Recharge
15:53
DEPTH OF WATER None
11
AFTER MONITORING:
16:03
10
DATE: 6/28/2005
17
.' 49th
Md E. A1109150M
No. U43it
BOH
S
L
0
P
E
READING DATE
GROSS
TIME
NET
TIME
DEPTH TO
WATER
NET
DROP
Start 6/24
15:42
6.75"
1
15:52
10
13.75"
7"
Recharge
15:53
6.69"
2
16:03
10
13.57"
6.88"
Recharge
16:04
6.75"
3
16:14
10
13.63"
.88"
FERC RATE: 1.4 MIN./INCH PERC. HOLE DIAMETER: 6"
TEST RUN BETWEEN 3.0 FT. AND 4.0 T.
COMMENTS: Test Hole Pre Soaked Prior To Percolation Test.
TEST PERFORMED BY: ALAN HARALA I, MICHAEL E. ANDERSON, CERTIFY THAT THIS TEST WAS PERFORMED IN ACCORDANCE
WITH ALL STATE AND MUNICIPAL GUIDELINES ON THIS DATE: 8/2/2005
2
3
4
5
6
7
8
9
is
11
17
MUNICIPALITY OF ANCHORAGE
DEVELOPMENT SERVICES DEPARTMENT/BUILDING SAFETY DIVISION
ON-SITE WATER AND WASTEWATER PROGRAM
4700 SOUTH BRAGAW ANCHORAGE, AK 99519
SOILS LOG - PERCOLATION TEST
PROJECT #:
PERFORMED FOR: Bob Bradley DATE PERFORMED: 6/22/2005
LEGAL DESCRIPTION: Nl/2, S1/2 NE1/4 SE1/4, NE1/4
TEST HOLE # 2 SLOPE SITE PLAN
OG/OL
GM
Poorly Graded
Gravel GP
GM
WAS GROUNDWATER
NET
TIME
ENCOUNTERED? NO
Silty Gravel
Start 6/24
15:25
IF YES, WHAT DEPTH?
Dark Gray
1
DEPTH OF WATER None
Damp
AFTER MONITORING:
.94"
DATE: 6/28/2005
ME
S
L
0
P
E
N
See Site Plan
READING DATE
GROSS
TIME
NET
TIME
DEPTH TO
WATER
NET
DROP
Start 6/24
15:25
10.56"
1
15:55
30
11.5"
.94"
Recharge
15:58
10.56"
2
16:28
30
11.44"
.88"
Recharge
16:30
10.5-
3
17:00
30
11.38"
.88"
PERC RATE: 33 MIN./INCH PERC. HOLE DIAMETER: 6„
TEST RUN BETWEEN 8.0 FT. AND 9.0 T.
COMMENTS: Test Hole Pre Soaked Prior To Percolation Test.
TEST PERFORMED BY: ALAN HARALA I, MICHAEL E. ANDERSON, CERTIFY THAT THIS TEST WAS PERFORMED IN ACCORDANCE
WITH ALL STATE AND MUNICIPAL GUIDELINES ON THIS DATE: 6/27/2005
2
3
5
6
7
8
9
17
MUNICIPALITY OF ANCHORAGE
DEVELOPMENT SERVICES DEPARTMENT/BUILDING SAFETY DIVISION
ON-SITE WATER AND WASTEWATER PROGRAM
4700 SOUTH BRAGAW ANCHORAGE, AK 99519
SOILS LOG - PERCOLATION TEST
PROJECT #:
PERFORMED FOR: Bob Bradley DATE PERFORMED: 6/22/2005
LEGAL DESCRIPTION: N1/2 S1/2 NE1/4, SE1/4, NE1/4
TGCT Ani F -1� 3 SLOPE SITE PLAN
OG/OL
Poorly Graded _
Gravel GP
WAS GROUNDWATER
ENCOUNTERED? NO
Silty Gravel IF YES, WHAT DEPTH?
Dark Gray DEPTH OF WATER None
Damp AFTER MONITORING:
DATE: 6/28/2005
BOH
S
L
0
P
E
N
See Site Plan
READING DATE
GROSS
TIME
NET
TIME
DEPTH TO
WATER
NET
DROP
Start 6/25
16:48
5.5"
1
16:58
10
14.25"
8.75"
Recharge
16:59
5.38"
2
17:09
10
14.5"
9.12"
Recharge
17:10
5"
3
17:20
10
14"
9"
PERC RATE: 1.1 MIN./INCH PERC. HOLE DIAMETER: 8"
TEST RUN BETWEEN 3.0 FT. AND 4.0 FT,
COMMENTS: Test Hole Pre Soaked Prior To Percolation Test.
TEST PERFORMED BY: ALAN HARALA I, MICHAEL E. ANDERSON, CERTIFY THAT THIS TEST WAS PERFORMED IN ACCORDANCE
WITH ALL STATE AND MUNICIPAL GUIDELINES ON THIS DATE: 8/2/2005
ANDERSON ENGINEERING
P.O. BOX 240773
ANCHORAGE, AK 99524
522-7773 522-6779 (FAX)
August 2, 2005
Municipality of Anchorage
Building Safety Division
On -Site Water and Wastewater Program
4700 S. Bragaw Street
Anchorage, AK 99507
Attention: Dan Roth
Subject: Bradley Subdivision, Lots 1 and 2
S-11382
Water Availability Study
Dear Dan:
We have collected information on the wells on several lots surrounding Bradley Subdivision
to estimate the possible depths and production rates of future wells to be constructed on the
two new lots proposed for the subdivision. Well logs were located for the lots in Stymans
Subdivision immediately north of this subdivision. Logs were also found for Spielman
Subdivision directly to the south of this parcel and Homestead Hills to the west. Flow tests on
the wells completed during health authority inspections were found on several of the wells
and provide additional information concerning water availability.
Wells studied vary in depth from 168' to 262' below the surface with the majority of the wells
near 200' in depth. The static water level varies from 120' to 215' below the surface. No
bedrock was noted on any of the well logs. The wells were drilled in mostly unconsolidated
soil formations consisting of gravel, silt and sand. These formations are generally more
productive for delivery of well water than bedrock formations. The wells are all lined with 6"
steel casing the entire depth with the pumping level near the bottom of the well. The
production rates noted on the well logs and flow tests varied from 4.9 to 20 gallons per
minute with the majority of the wells more than 10 gallons per minute.
In conclusion, it is highly likely the wells to be constructed at Bradley Subdivision will be
approximately 200' in depth with a range between 170' and 220'. They will be constructed in
unconsolidated soil formations and require casing the entire depth. Production rates from the
well will be between 5 and 20 gallons per minute. Actual water system production will
depend on the size of the pump placed in the well and the interior plumbing in the house. It is
Bradley Subdivision
August 2, 2005
Page 2
apparent, based on our study and the results achieved on the wells surrounding this property
that sufficient water is available for the development of the two lots in the proposed Bradley
Subdivision.
Please let me know if you have further questions.
Sincerely,
Michael E. Anderson, P.E.
Attachments
MICHAEL E ANDERSON
. No. CE -4381
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