20200357 Ver 2_SHWT Report_20210209

February 9, 2021
Job # 10842.S1
Marlowe & Moye, LLC
Attn: Howard Moye
PO Box 20667
Raleigh, NC 27619

Re: Detailed storm water soils evaluation at 7401 Hilburn Road, Raleigh, NC.

Dear Mr. Moye:

Soil & Environmental Consultants, PA (S&EC) performed a detailed soil evaluation within
the targeted area of the potential storm water BMP on the site mentioned above (see attached
map for the soil boring location). The purpose of this evaluation was to provide additional
information for the proper design of the proposed bio-retention area to treat the on-site storm
water. A soil morphological profile description was performed at the specified location to
determine depth to seasonal high water table (SHWT). The following is a brief report of the
methods utilized in this evaluation and the results obtained.

Soil/Site Evaluation Methodology

The site evaluation was performed by advancing hand auger borings to sufficient depths to
estimate seasonal high water table. S&EC navigated to the soil boring location to describe
soil morphological conditions using standard techniques outlined in the “Field Book for
Describing and Sampling Soils, Version 3” published by the Natural Resources Conservation
Service (NRCS, 2012).

Soil/Site Conditions

This site is located in the Acid Crystalline geological area of Wake County. Soil Boring 1,
located in bio-retention area, was advanced 65 inches from the top of existing ground until
hand auger refusal. Field investigation revealed seasonal high water table indicators at 30
inches below top of existing ground at the Soil Boring 1 location.

A soil profile description for Soil Boring 1 is shown below.
Horizon
Depth
Matrix Color
Texture
Mottles
Other notes
inches
A
0 — 11 in
Brown
Sandy Loam
Bt
11 — 30 in
Light Reddish
Clay
Brown
BC
30 — 65 in
Gray
Fine Sandy
Black,
SHWT @ 3V
Loam with
Light Gray
clay lenses
AR
65 in
Auger
Refusal
Each storm water device has different requirements with regard to in -situ soils. Under current
regulations, the bottom of any bio-retention area must be a minimum of two feet above the
seasonal high water table. Current NC-DWR regulations also stipulate that an underdrain
must be installed in a bioretention basin if soils underlying the structure have a drainage rate
of less than 2 in/hr. S&EC made no attempt to measure soil saturated hydraulic conductivity
(Ksat) in the underlying soil at this time but, due to the underlying clay horizons, S&EC
believes that the hydraulic conductivity would be less than 2 in/hr.
Soil & Environmental Consultants, PA is pleased to be of service in this matter and we look
forward to assisting in the successful completion of the project. If requested, S&EC can meet
on -site with NC-DWR to discuss our findings and recommendations. Please feel free to call
with any questions or comments.
Sincerely,
Soil & Environmental Consultants, PA
Ricky Pontel
NC Licenses'
Page 2 of 2

HILBURN DRIVE(EX. 60' PUBLIC R/W)846-94678412 Falls Of Neuse Road
www.SandEC.com
27615NorthRaleigh,Carolina 846-5900Phone:(919)Fax:(919)
STORMWATER SOILS EVALUATION
WAKE CO., NC
7401 HILBURN ROAD
Location:
Project:
Sheet Title:
Client:
1 of 1
10842.S1
Field Work:Scale:
1"=10'
Sheet No.:
Project No.:
Project Manager:
RP
Drawn:
RP
RPMARLOWE & MOYE, LLC
SOIL BORING 1
SHWT 30"