HomeMy WebLinkAboutWOHLFORTH ACRES S12306Onsite File
a 0 0
Tmnry;1i
#5 12306
November 11, 2016
Municipality of Anchorage
Development Service Department
On -Site Water & Wastewater Program
4700 Elmore Road
Anchorage, AK 99507
Attention: Deb Wockenfuss
Subject: Soils Investigation Report and Septic Reserve Area for the
Proposed Subdivision of WOHLFORTH ACRES; LOTS 1 & 2 IN ANCHORAGE,
Alaska (A SUBDIVISION OF KINCAID ACRES S/D; LOT 3)
Mrs. Wockenfuss,
The referenced property is located off Ingram Street in Anchorage, Alaska. Based on the
preliminary plat drawing provided to us, Kincaid Acres S/D; Lot 3 is proposed to be subdivided
into two lots, Wohlforth Acres S/D; Lot 1 & 2. The current lot (Kincaid; Lot 3) has an existing
house located on it with an MOA approved well and septic system. We have excavated and
logged a test hole on the proposed undeveloped lot that has been used to establish a septic
reserve area for the proposed subdivision. The proposed lot will be served by AWWU water
and an onsite septic system.
PROPOSED SEPTIC RESERVE AREAS
We have prepared soil logs for the test hole (see attached). Per MOA wastewater ordinance
AMC 15.65.180, we are required to provide a site map showing a septic reserve area for each
lot that meets the requirements set forth in Table 2 of AMC 15.65.180 (see below).
=1c 0
TABLE INSET:
Percolation Rate
minutes/inch
Total Reserved Area (square
feet
1--5
10,000
5--12
12,000
12--24
14,000
24--60
16,000
3701 East Tudor Road, Suite 101 *Anchorage, Alaska 99507-1259
Phone: (907) 337-6179 * Fax: (907) 338-3246 * Website: www.garnessengineering.com
Page 2 of 2
The percolation result for test hole #2 (proposed Lot 1) was 8.6 minutes/inch. Based upon
Table 2, proposed Lot 1 requires a septic reserve area of 12,000 square feet. Attached is a site
plan which shows the septic reserve area for the proposed lot. As can be seen on the site map,
which has topographical information established by The Boutet Co., the slopes within the septic
reserve areas range from 0% to 40%. There appears to be sufficient area for a structure,
driveway, and onsite wastewater disposal system for the proposed lot.
SLOPE WAIVER REQUEST FOR SEPTIC RESERVE AREAS:
As can be seen on the site plan, the average slopes within the septic reserve areas range from
0 to 40 percent. We are requesting a waiver for the proposed lot to allow the septic reserve
areas to be used for these slope conditions. The following are mitigating factors for justification
of these waivers:
• Based upon the percolation results, the porosity of the soils is good and will promote
rapid downward movement versus lateral movement of the effluent.
• The slopes below the platted drainfield sites are heavily vegetated.
• It is reasonable to assume we could stay 50 feet from slopes that are greater than 25%
with a proposed septic system.
• As can be seen on the attached slope waiver drawing, a line drawn 2 feet above the top
of rock in a theoretical trench with 4 feet of effective would not intersect until 37 feet with
a 40% slope.
Given these mitigating factors, it is our opinion that there is minimal risk with the granting of this
waiver.
WATER AVIALABILITY:
The proposed lot is stubbed by AWWU water. However, if drilling a well was necessary. A well
flow test was performed on the existing well for Kincaid Acres; Lot 3 on 7/13/2016. It was
determined the well could produce at least 4.8+ gallons per minute. Based upon this fact, it is
reasonable to assume that there will be no issues in regards to water availability.
If you have ari
,V gyestions, please contact us at 337-6179.
0
Jeeffr,, arness?P.E., M.S.
Pres', en
3701 East Tudor Road, Suite 101 * Anchorage, Alaska 99507-1259
Phone: (907) 337-6179 * Fax: (907) 338-3246 * Website: www. garnessengineering.com
'ARNESS ENGINEERING GROUP, Ltd
CIVIL & ENVIRONMENTAL ENGINEERS.. - ;_.
3701 E. TUDOR ROAD, SUITE 101 • ANCHORAGE, AK 99507 -PHONE (907) 337-6779' FAX (907) 338-3248 • WEBSITE: w.w�.gamassengineenng.com
SOIL LOG — PERCOLATION TEST
LEGAL DESCRIPTION: WOHLFORTH ACRES; LOT 1
PERFORMED FOR: ERIC WOHLFORTH DATE: 9/9/2016
DEPTH
(feet) ORG ITEST HOLE #2
1
2
SOIL CLASSIFICATIONS
SITE PLAN
GW
ORG
3
=` s= GP
ML
GM
CL
4
GC
OL
SW
MH
5
: SP
CH
SM
�
� ,' OH
6
SC
7
DEPTH TOA
DATE
GROUNDWATER
��
N
8-1
DRY
9/9/2016
DRY
10/7/2016
SCALE:
9
SM
1" =100'
10
DATE READING
CLOCK
NET TIME
WATER LEVEL
NET DROP
11
TIME
(MINUTES)
READING
(INCHES)
12
9/12/2016
1
3:20
6"
"
2
3:30
10
2 - 1/8"
4 - 7/8"
13
3
3:30
-
6"
-
4
3:40
10
2-3/8"
3 - 5/8"
14
5
3:40
-
6"
"
6
3:50
10
2 - 4/8"
3 - 4/8"
15
7
3:50
6"
-
16
8
4:00
10
2 - 4/8"
3 - 4/8"
9
4:00
6"
"
17
B.O.H.
10
4:10
10
2 - 4/8"
3 - 4/8"
11
4:10
6"
"
18
12
4:20
10
2 - 4/8"
3 - 4/8"
19
PERCOLATION RATE 8.57 (MIN./INCH) PERC. HOLE DIA.
—
TEST RUN BETWEEN 5 FT. AND 6 FT.
20 A FOUR HOUR PRESOAK WAS PERFORMED:
YES ❑ NO
SOILS LOGGED BY: DAVID GARNESS PERCOLATION TEST PERFORMED BY: ERIK WIDGER
COMMENTS: PERCOLATION READINGS ARE WITHIN 1/16 OF INCH.
PERFORMED BY GEG, Ltd. I, JEFFREY A. GARNESS, CERTIFY THAT THIS WAS PERFORMED IN ACCORDANCE
WITH ALL STATE AND MUNICIPAL GUIDELINES IN EFFECT ON THIS DATE:
6 (INCHES)
lam'
\ o o •
3 4
\ / I
41
Ci -
1
co 7
-- ------ -