SW6180702_AddInfo2_20180823 (3)

August 23, 2018

Leslie Hartz, Vice President - Pipeline Construction
Dominion Energy Transmission, Inc.
5000 Dominion Blvd.
Glen Allen, VA 23060

Subject: Request for Additional Information
Stormwater Permit No. SW6180702
ACP Fayetteville Contractor Yard – CY10a
Cumberland County

Dear Ms. Hartz:

The Division of Energy, Mineral and Land Resources (DEMLR) received a Stormwater Management
Permit Application for the subject project on July 20, 2018 and additional information via telephone on
August 22, 2018. A review of the application has determined that additional information is needed to
meet the requirements of 15A NCAC 02H . Failure to provide the following additional information to
DEMLR by September 23, 2018 will result in the application being returned as incomplete. If the project
is returned, then a resubmittal of all required items is required, including the application fee.

Please address the following plan deficiencies:

1. Draw Down Time [Ref. 15A NCAC 02H .1051(5)]
In-situ soils may be removed and replaced with infiltration media if the applicant demonstrates
that the modified soil profile allows for infiltration of the design volume within 72 hours or less.
Provide a detailed specification for the select fill material in the infiltration trenches that will
ensure the required draw down time is provided.

2. Seasonal High Water Table Separation [Ref. 15A NCAC 02H .1051(2)]
Cumberland CY Cross-Sections plan sheet 5 of 9 provides existing ground elevations of 89.4 and
90.0 for infiltration trenches 221 and 222, respectively. Existing grade contours shown on the
plans would appear to indicate existing grade at approximately 92 feet for both devices. The
submitted soils evaluation places the SHWT elevations at 91.6 and 90.9, respectively. This
discrepancy makes compliance with the minimum requirement for a 2-foot separation between
the SHWT and the lowest point of the infiltrations system (shown as 91.0 feet for both devices)
difficult to confirm. Please confirm the existing grade elevations and 2-foot separation to the
SHWT and provide documentation to support these determinations. The two tables below may
help illustrate this point. The orange highlighted numbers are in question. Please substantiate
these numbers.

Table 1: Plan Reviewer Evaluation – No SHWT Separation
Source Infiltration Trench 221
Elevation (ft)
Infiltration Trench 222
Elevation (ft)
Existing Contours Sheet 5 Topo 92.0 92.0
SHWT* Soils Evaluation 92.0 - (5”/12) = 91.6 92.0 - (13”/12) = 90.9
Bottom of Device Sheet 5 Details 91.0 91.0
SHWT Separation Computed 91.0 – 91.6 = (0.6) 91.0 – 90.9 = 0.1
* The soils evaluation lists depth in inches to SHWT from ground surface, elevations calculated as shown.

Table 2: Submitted Plans – 2.0 Foot SHWT Separation Provided
Source Infiltration Trench 221
Elevation (ft)
Infiltration Trench 222
Elevation (ft)
Existing Ground Sheet 5 Details 89.4 90.0
SHWT Sheet 5 Details 89.0 88.9
Bottom of Device Sheet 5 Details 91.0 91.0
SHWT Separation Computed 91.0 – 89.0 = 2.0 91.0 – 88.9 = 2.1

Please note that the separation may be reduced to no less than 1-foot, if a hydrogeologic
evaluation demonstrates that the water table will subside to its pre-storm elevation within five
days or less (see NCDEQ Stormwater Design Manual A-2 for guidance). If these criteria cannot
be met, then another type of device is required to be utilized.

3. It is recommended that Detail 4 and the associated construction specifications for the infiltration
trenches located on Erosion and Sediment Control Plan Details (page 7 of 9) be referenced on
Cumberland CY Cross-Sections (sheet 5 of 9) so that it is not overlooked by the contractor.

4. Please include dimensions for Infiltration Trench 221 on the plans.

Please reference the State assigned project number SW6180702 on all correspondence. If you need
additional time to submit the information, please submit your request for a time extension to the Division
at the contact below. The request must indicate the date by which you expect to submit the required
information. The Division is allowed 90 days from the receipt of a completed application to issue the
permit.

The construction of any impervious surfaces, other than a construction entrance under an approved
Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement
action pursuant to NCGS 143-215.6A.

If you have any questions concerning this matter please feel free to contact me at
[e-mail] or [phone].

Sincerely,
Jeanette Powell
Environmental Engineer

Stormwater Program

Cc: Staci Roggi, Dominion Energy
Richard Gangle, Dominion Energy
Mr. Scott A Robinson, PE, ERM NC, Inc.
DEMLR Fayetteville Regional Office