9231_BrownfieldRdCDLF_Phase3DesignHydroAppr_FID1835353_20240502

May 2nd, 2024

Sent via Email – [e-mail]

Mr. Donald Plessinger
Wake Reclamation, LLC
General Manager
2600 Brownfield Road
Raleigh, NC 27610

Re: Design Hydrogeologic Report – Southern Expansion Area
Brownfield Road CDLF
Permit# 9231-CDLF-2012
FID 1835353

Dear Mr. Plessinger,

The Division of Waste Management, Solid Waste Section (Section) has reviewed the Design Hydrogeologic
Report – Southern Expansion Area (FID 1821835) for the facility submitted by Smith Gardner, Inc. (S+G)
on behalf of Wake Reclamation, LLC. The southern expansion area will be comprised of approximately 24
acres located south of Phases 1 and 2.

The hydrogeologic investigation was conducted using data from 13 pre-existing exploration borings in
addition to five historic monitoring wells, 15 newly installed piezometers, and four recently advanced soil
borings in and adjacent to the proposed footprint. Borings indicated the presence of silty sand/sandy silt
and sandy clay above the partially weathered rock. Auger refusal was encountered at depths ranging
from 2 to 50 feet below ground surface across the southern expansion area footprint. Partially weathered
rock was observed at depths ranging from 4 to 35 feet below ground surface. A geophysical survey
indicated the presence of two minor and one major diabase dike in the southern expansion area. The two
minor dikes begin as one and the second is a splay of the first. The major diabase dike is located in the
western portion of the site near the western tributary. Based on the cross sections presented in Figures
7 through 9, the vertical separation between the proposed base grade and top of bedrock elevations
ranged from approximately 6 to 56 feet.

Sixteen piezometers and 10 monitoring wells were utilized to evaluate hydrogeological conditions in the
Southern Expansion area. The uppermost unconfined aquifer was observed to have an approximate
elevation ranging from 260 to 200 feet above mean sea level. The general direction of groundwater flow
through the unconsolidated sediments and partially weathered rock is to the north northwest towards
the unnamed tributary of the Neuse River. S+G utilized data from rising and falling head tests from 16
piezometers to calculate an average hydraulic conductivity for the Southern Expansion Area of 5.25 x 10-

5 ft/day. The average groundwater gradient in the expansion area was calculated to be 0.0341 ft/ft while
the average velocity was 0.1298 ft/day. Six nested pairs of piezometers and two nested pairs of
monitoring wells were used to calculate vertical gradients in areas within and adjacent to the southern
expansion area. Downward vertical gradients were observed in nested monitor well pair (MW-6AS/AD)
and nested piezometer pair (PZ-9S/9D) located approximately 400 feet north of the proposed waste
boundary and within the southern disposal area, respectively. Upward hydraulic gradients were observed
in the remaining nested pairs in areas north and west of the proposed waste boundary. Based on the
cross sections presented in Figures 7 through 9, the vertical separation between the proposed base grade
and long term seasonal high groundwater elevation ranged from approximately 5 to31 feet.

Based on the results of the Design Hydrogeologic report, proposed Southern Expansion Area fulfills the
requirements specified in 15A NCAC 13B .0538(b) and is suitable for expansion. Please contact me at
[phone] or by e-mail at [e-mail] if you have any questions or concerns regarding
this letter. Thank you in advance for your cooperation in this matter.

Sincerely,

Ervin Lane
Hydrogeologist
Solid Waste Section

Cc sent via email: Perry Sugg, P.G. – SWS Environmental Compliance Branch Head
Sherri Stanley – SWS Permitting Branch Head
John Nguyen – SWS Permitting Engineer
Tim Davis – SWS Environmental Senior Specialist
Joan Smyth, P.G., – Smith Gardner, Inc.
Mike Brinchek, P.E. – Smith Gardner, Inc.
Bryan Wuester – GFL Environmental, Inc.