SW8960615_COMPLIANCE_19960717

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW
DOC TYPE
❑ CURRENT PERMIT
❑ T APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE-
& � ]
YYYYM M DD

-7
777
..r ,....�
ENGINEERING
Stocks and Tripp, Consulting Engineers
211 North Fifth Avenue
Wilmington, North Carolina 28401
Attn: Mr. Phil Tripe
Ref Infiltration Evaluation
Yarborough Transfer Property
Wilmington, North Carolina
Job No. 934-96
Dear Mr. Tripp:
7650 MARKET STREET
MLMINGTON, NORTH CAROLINA 28405
April 15, 1996 OFFICE: 910-686-9114
FAX: [phone]
S����[NA�E�
D E C E I V E
JUN 171996 D
PROJ # _?WM0C01S
Soil Tech Engineering, Inc. has recently conducted an evaluation of the existing subsurface
conditions at the Yarborough Transfer site located on Highway 421 north of Wilmington, North
Carolina.
As requested, representatives recently visited the site to investigate the subsurface conditions
within the proposed retention pond area. The subsurface conditions were investigated by drilling and
sampling the eXI'sting soils to a depth of approximately 16 feet below the ground surface. During the
investigation, groundwater was encountered at elevation 89,
While on -site. Our re- .-sen*ative connducted an infiitration s#.udy of the rate of the cljbs>!r-F—p
conditions at approximately elevation 92, This elevation is above the present design retention pond
bottom because of the minimum separation above the seasonal high groundwater table. From our
investigation, we estimate that the seasonal highwater table is approximately elevation 90. Our
infiltration testing indicates that a maximum rate of 15-17 inches per hour should be used for design
of the retention pond.

Yarborough Transfer
Wilmington, North Carolina
Page Two
Attached please find the results of our field and laboratory testing and a sketch of the areas
tested. If you have any questions, please contact us.
Very truly yours,
SOIL TECH ENGINEERING
�G1, ttb
Parks A. Downing, Jr.
Manager
James Pate, P.E.
PADjr;JP/ml
934a4-15
Attachments

SUBSURFACE PROFILE
YARBOROUGH STATION
0.0 - LEGEND
SAND
5.0
10.0
15.0 -
20.0
aS ��
[Yarborough Trudci ng , W4
wi1nriru on, Nbrth Carolina
Job No. 934-96

Approximate location
of retention pond
Building
N.C. tWY 421
SOI
A DENOTES LOCATION OF INFILTRATIGU TE5TI11C-1 Fmgbf
Yarborough Trucking
Wi 1 rd ngtcn, North Carol i na

LOCATION:
DEPTH: (FT)
51E VE SIZE
#10
440
980
#200
PERCENT MOISTURE:
SOIL DESCRIPTION
GRAIN SIZE ANALYSIS
YARBOROUGH TRUCKING FACILITY
WILMINGTON, NORTH CAROLINA
JOB NO. 934-96
#1
#2
8.0'
13.0'
PASSING,
BY WEIGHT
100,0
1000
85.6
55.7
5.6
9.5
1.1
2.3
5.8%
4.0%
Light Tan
Cream/White/Gray
Fine to Medium
Mixed Fine to
SAND
Medium SANND