WQ0042579_Hydrogeological Report Review_20210917

Hydro�zyeolo�zyical Investigation Report Review Form
Application / Permit Number: WQ0042579
Primary Permit Reviewer: Lauren Raup-Plummer Date submitted for review: 06/04/2021
Hydrogeological Investigation Report Reviewer: Poonam Giri Review completed:09/17/2021
All pertinent elements complete: Yes or El-Ne. If no, please list missing information:
• report signed & sealed by a PE, LG or LSS?
• cursory examination of nearby properties & wells within 500 feet
• field observations
• maps (topographic, overview, and site detail)
• published reports
• sufficient number of bore holes with drilling/sampling logs in the area of system operation
• sufficient number of wells with drilling/sampling logs in the area of system operation
• shallow aquifer tests with detailed supporting data and appropriate analyses
• groundwater modeling results with supporting test data and reasonable assumptions
• others?
2. Field visit conducted? 9 Yes or FINo. If yes, was the physical information contained in the
hydrogeological investigation report verified by the field observations? ❑ Yes or ❑No. Please list
any discrepancies:
3. Aquifer parameters were determined by: ❑ Pumping Test ❑ Slug Tests ❑ Estimated from a
Soil or Geologic Publication ❑ Other method:
4. Mounding analysis submitted? ❑ Yes or ❑No. If no, please provide commentary on necessity:
MODFLOW was used to demonstrate groundwater mounding within the high -rate infiltration sites at
Mulberry Branch. Due to the and resolution of the figures (Figure 7), it is difficult to scrutinize the
mounding analysis for the relocation and high -rate sites.
Was it necessary or advisable for you to confirm the assumptions/results through independent
modeling or calculations? ❑ Yes or ❑ No I did not confirm the mounding results.
Methodology used for analysis adequate? Yes or fie. If no, please list areas of concern: The
only comment I have on the water balance for the relocation sites is that the PAN evaporation data
used is for Lumberton, NC. These values may not reflect more coastal evaporation behavior at the
site.
5. Approximate depth to groundwater mound at steady state: Basin A: 64.7ft , Basin B: 64.7 ft , Basin
C; 64.5 ft
6. Site conditions to be maintained as assumed in the analysis (e.g. drainage features):
Soils, including all silty and clayey deposits will be excavated to a depth of 54 feet amsl. High
efficiency drains are to be utilized for the high -rate sites. The drains will be at 50 ft amsl and spaced
at 100 feet, to ensure a gradient for irrigation on the high -rate sites. Basin A is partially in the
floodplain and the berm is intended to provide protection. The berm should be periodically assessed
to maintain structural integrity.
7. Contaminant Transport analysis submitted? ❑ Yes or ❑No. If no, please provide commentary on
necessity: Transport analyses were not conducted for the Shallotte relocation sites.
8. Was it necessary for you to confirm the results through independent modeling or calculations?
9 Yes -or No. I did not perform independent modeling or calculations for the site. Contaminants
are unlikely to be problematic for the proposed effluent quality.
9. Effluent quality used in analysis demonstrating protection of 2L standards (e.g TN = 10mg/1): Solute
transport analyses were conducted (MT3D simulation) for Nitrogen in the high -rate sites. The results
Hydrogeological Report Review Form

of this simulation reflect that Nitrogen standards will be protected at the compliance boundary. The
effluent water quality is protective and should ensure metals, solids, and nutrients will not exceed 02L
standards.
10. Concerns with protection of 2L standards at the Compliance Boundary? ❑—Yes or No. If yes,
please list areas of concern:
11. Are monitor wells needed at this facility? Yes El-#e. If yes, do the number and locations of the
monitor wells proposed in the hydrogeological report concur with the recommendations of the APS?
Yes. 11 wells have been proposed for the site to surround the infiltration basins. MW BA 1
satisfies the need for a monitoring well in the portion of irrigation area that is situated in the 100 year
floodplain. Well MW Wland MW WW2 ensure that exceedances will be discovered prior to any
impact to the existing wetland area.
The number and locations of the monitor wells should consider such factors as the size of the
application area, the locations of the Compliance and Review Boundaries, and the existence of nearby
water supply wells. The recommended substances to be monitored and comments are as follows:
Standard groundwater parameters with the effluent proposed.
12. The hydrogeologic report should meet the standards described in the Aquifer Protection Section's
Hydrogeologic and Reporting Policy and Groundwater Modeling Policy of May 31, 2007.
Specifically, does the report:
• Focus on the waste application area? ❑ Yes ❑ No The report is somewhat disorganized as both the
characteristic of the Shallotte relocation sites and the new high -rate infiltration sites are included and
discussed interchangeably.
• Include borings advanced to a depth of 20 feet or more? Yes D No
• Include enough borings in appropriate locations to create a reasonable hydrogeologic
conceptualization of the waste application area? ❑ Yes D No
• Include a sufficient number of slug tests or pumping tests that were properly performed and analyzed
for basic hydrogeologic parameters? ❑ Yes [ #eA total of 7 tests were conducted, with 5 of them
in the high -rate infiltration area. Of these, only one test was unable to estimate specific yield.
• Utilize appropriate calculations or computer software to assess the potential for mounding beneath the
application area and/or contaminant transport beyond the Compliance Boundary? ❑ Yes El Pie
• Use recognized assessment methods that are consistent with standard scientific practices and
interpretations? -❑ Yes El-#e MODFLOW and MT3D are widely utilized and are well -established
means for analysis.
• Have analyses and/or conclusions which include "safety factors" such as conservative assumptions to
compensate for gaps in the field data or questionable test results? ❑ Yes E-#e
Calculations and model parameters represent reasonable and field verified values.
13. List in detail any additional information or items that are needed to evaluate the site: Additional
detail of "high efficiency" drains will be helpful. The basins will be dependent on the functionality of
the drain system. Is there a potential for interaction of the drains with the wetland areas and
floodplain? If not included in sufficient detail within the Plans and Specifications, information on
these drains should be requested.
Also, a hydrogeologic report specifically discussing the Shallotte relocation sites (under permit
WQ0000798) and impact of the irrigation sites on the will be necessary. Monitoring wells should be
proposed for the relocation sites.
Any hydrogeologic information received for WQ0000798 may also be considered along with the
report for this project.
14. List in detail any special conditions related to groundwater monitoring or hydrogeologic issues that
should be included in the permit: None recommended at this time.
Hydrogeological Report Review Form

Other areas of concern or note:
• Water supply wells in area
• Mounding is a potential limiting factor in the water balance
• New, experimental, or otherwise unproven treatment technology
• etc.
15. Recommendation on permit issuance*: ❑Issue �Berzy
❑ Request additional info. based on above comments.
* - based on hydrogeological investigation report
Reviewer's Signature: ?v�
Date: 09/17/2021
Hydrogeological Report Review Form