WQ0037287_More Information (Received)_20191202

Michael C. Gallant PE, PA
Engineering / Consulting / Design
NC Firm C-1989, AL Firm CA - 4338 - E
NC Reg. No. - 25572, AL Reg. No. - 32178
November 27, 2019
Linda Culpepper
Director, NCDEQ Division of Water Resources
512 N. Salisbury St.
Raleigh, NC 27699-1617
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Re: Pluris Hampstead WWTF — WQ0037287 — Request for Variance for Alternative Design Criteria
Linda,
I have received a request for additional information regarding the permit modification for the Pluris Hampstead
WWTF. The letter states the following:
1. Per 15A NCAC 02T .0705(w), the application rate shall not exceed 10 gallons per day per square foot. The
applicant may request Alternative Design Criteria per 15A NCAC 02T .0105(n). Provide a demonstration that the
alternative will provide: a. Equal or better treatment of the waste; b. Equal or better protection of the waters of the
state; and c. No increased potential for nuisance conditions from noise, odor, or vermin.
2. Due to the increased disposal rate, address how the Permittee will prevent the storage pond from overtopping.
Are these plans addressed in the Operation and Maintenance Plan?
My responses are as follows:
Item 1
During the modification of this permit which began with the original application submitted to your office in May of 2018
the rule regarding the maximum rate of application to a high rate infiltration (HRI) basin was established. I attended
the stakeholder meetings regarding this matter and I discussed my reservations about this rule with Mr. Nathaniel
Thornburg. I also commented on the rule vial email.
I had several concerns at the time. The first was that I did not see a reason for an upper limit on the application of
effluent to an HRI basin. The second issue was that the value of 10 gallons per day per square foot seemed arbitrary.
Why not 9 gpolsf or 11 gpd/sf? Was this limit based on any measured reproducible data or field experience?
I relayed these concerns to Mr. Thornburg at the stakeholder meeting and he assured me at the time that the rule
was to rein in bad actors who would try to submit irresponsible designs, unlike the established and historically tested
designs of the two Pluris facilities that had been constructed at that time.
Subsequently, I submitted a permit modification package based on the criteria the plant was originally permitted
under. This included a water balance signed and sealed by a NC licensed professional geologist. This water
balance included the groundwater impoundment as it was required to do in the original permitting.
[e-mail]
tel [phone]
P.O. Box 4039
Surf City, NC 28445

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Michael C. Gallant PE, PA
Engineering / Consulting / Design
NC Firm C-1989, AL Firm CA - 4338 — E
NC Reg. No. - 25572, AL Reg. No. 32178
NCDEQ staff responded that they would require Pluris to do a 6 month pilot study of the HRI basins taking the
groundwater impoundment out of the equation. This included a short term 24 hour period of intense loading of each
basin in order to reach a steady state maximum flow for each basin. In subsequent emails and phone conversations
with Wilmington Regional Office Staff I reiterated that I believed this methodology would yield a large increase in
available flow. This study was completed as instructed by NCDEQ and Wilmington Regional Office Staff was
contacted and came to the site prior to the beginning of the study and during the two 24 hour intensive loading
periods for each basin.
That said, my response to the three criteria stipulated in the request for additional information are below.
a. Equal or better treatment of the waste.
Increasing the MBR treated disposal capacity of the high rate infiltration basins will not affect the quality of
the effluent since the treatment of the waste occurs prior to disposal. During our pilot study we saw no
degradation of the HRI basins or changes to the effluent quality with the increased flows.
b. Equal or better orotection of the waters of the state.
This is a non -discharge disposal system that does not directly impact waters of the state. The increased
flow will result in an increase of surplus groundwater in the groundwater impoundment. Being groundwater,
this basin and its contents are not regulated. Currently the plant flow is approximately 90,000 gallons per
day. This flow is managed easily on -site by natural infiltration in the groundwater impoundment and by
some very limited use as irrigation for street trees at the plant entrance. If for any reason it would be
needed, there is additional acreage owned by Pluris Hampstead that could also be used for irrigation. The
long term goal is for the third party that owns the impoundment to monetize the groundwater and sell it to a
homeowner's association for irrigation purposes in the planned surrounding subdivision.
c. No increased ,',otenfial for nuisance conditions from noise. odorr and vermin.
As stated above, this issue concerns treated effluent disposal. This is a gravity system with no pumps
associated with it. There is no noise generated with the system other than the trickle of water over the weirs
and in the basins. The effluent does not have a distinct odor and does not attract vermin. AS NCDEQ
already acknowledges, the MBR treated effluent that has typically less than 0.1 turbidity, and by permit
requirements less that 4 mg/L of Total Nitrogen and less than 2 mg/L of Total Phosphorus.
Item 2
I believe that the first sentence in item two is answered in my response to (b) above. The second question asks
about the inclusion of the pond in the maintenance and operation plan. Please note that this pond (the surplus
groundwater impoundment) is not part of the permitted treatment works and is owned by a third party. At the time of
permitting, Pluris executed a long-term contract that states that Pluris is responsible for the maintenance and
operation of the impoundment.
[e-mail]
tel [phone]
P.O. Box 4039
Surf City. NC 28445

F=
Michael C. Gallant PE, PA
Engineering / Consulting / Design
NC Firm C-1989, AL Firm CA - 4338 — E
NC Reg. No. - 25572, AL Reg. No. - 32178
Additional Comments
During this entire process Pluris has endeavored to meet or exceed all of the requirements set out by the NCDEQ
Central and Regional office staff. We have spent a considerable amount of time and money on the application and
pilot study process. The pilot study was conducted and completed under the direction of the Regional Staff.
Based on the responses given above I respectfully request a variance from the aforementioned rule, 15A NCAC 02T
.0705(w), regarding the maximum loading rate for the HRI basins of 10 gallons per day per square foot.
If you have any questions regarding this matter, please feel free to contact me.
Sincerely,
Michael C. Gallant, PE
gallantmcCyahoo.com
tel [phone]
P.O. Box 4039
Surf City, NC 28445