WQ0037287_Correspondence_20240819

PLURIS MAURICE W. GALLARDA, PE
Managing Member
August 19,2024
ZacharyJ. Mega
Environmental Engineer 111
Division of Water Resources - Non-Discharge Branch
North Carolina Department of Environmental Quality
512 N. Salisbury Street
Raleigh, NC 27699
Letter via email to [e-mail]
Nathaniel D. Thornburg
Environmental Program Supervisor II
Division of Water Resources - Non-Discharge Branch
North Carolina Department of Environmental Quality
512 N. Salisbury Street
Raleigh, NC 27699
Letter via email to [e-mail]
Re: Technical Information
Zachary and Nathaniel,
First and foremost, thank you for the effort on the new non-discharge permit for Hampstead, I recognize DEQ needs
additional staffing in light of the growth in the state.
I am sending you both this letter and it is my sincere technical hope that it might offer some perspective regarding
Pluris. I waited until we completed the non-discharge permit so as to not distract you in the review of the permit. As
you may know we are also working with NPDES folks in Raleigh, who in turn are working with the North Carolina
Collaboratory and Region 4 of the EPA on discharges into low and zero flow streams, and in transparency of all
correspondence, I am copying Julie Gryzb, Michael Montebello, Richard Rogers, Jeff Warren, Craig Hesterlee,
Daniel Holliman and our design engineer Michael Gallant.
If only one thing comes out of your review of the information presented, it would be that Pluris, unlike some utilities,
invests considerable capital into studying what we do to help us in future treatment design that, in turn, helps
communities while protecting and enhancing the environment. It is important to note that these investments are not
allowed in the North Carolina Utilities Commission approved rates to customers, but we are not concerned with that.
Some of these investments are presented in this letter.
In reviewing the non-discharge permit Paragraph 1 of Section 1., "Schedules", reads,
"In accordance with correspondence from the United States Environmental Protection Agency, any
unpermitted discharge to surface waters of effluent collected via the engineered material is a
violation of Section 301 (a) of the Federal Clean Water Act."
T:214.220.3412 I F:214.965.9090 I [e-mail]
Page 1 of 7
I am not complaining, I just disagree with the statement. The referenced correspondence were two letters in the
summer of 2014. I have attached a copy of the June 26, 2014 letter then "DENR" sent to the EPA, and EPA's
response letter dated July 14, 2014 back to DENR. Note that nowhere in the EPA correspondence is the statement
that, "the engineered material is a violation of Section 301 (a) of the Federal Clean Water Act".
The description of the material in the DENR letter characterized the engineered material as a "(e,g., coarse sand or
gravel)." The DENR also states,
",. that the engineered material sen/es as a man-made conduit to surface water."
The referenced correspondence between the DENR and EPA did not involve Pluris, Had Pluris been allowed to
respond prior to the DENR letter being sent to the EPA, Pluris would have provided previously conducted American
Standards of Testing Materials ("ASTM") testing of the non-native material to DENR. It should be noted that the
DENR permitter for the project had not actually visited the high rate infiltration pond to observe the non-native
material during permitting including up to the time the letter was sent to EPA. The engineered ("non-native") material
was not some synthetic material, but rather simply crushed rock from a quarry. The material, as classified by the
ASTM D-422 test method is shown in the following test results table (yellow highlighted area) to be a fine to coarse
grain sand. In fairness, approximately 5% fell into a pea gravel size (1/8"-1/4" diameter size) and on the other end,
approximately 5% was comprised of clay.
1.5" 1"3/4" 3/8"in m ina ff-io ff6o wioo M200
100%
90%
80%
70%
60%
50%
w%
30%
20%
10%
0%
obbles and gravel n
t______ . . A_—_ A^- A_AI ' T '!'!!' l-^lT^T
I ' i ' U ! ' I i ^ 'T
{\ li. ! i'ii FT-T
' L^
IV - _^_-_LLIT^..J^ i1\ ••' ^~- —Ti T': ! Iy"\—-I
m ; ; , ' : i
fine to coarse grain sand range
i ^: \' ",1 i I ^ '-^ \
J_! \\ ^ : • ! I i ^ ' ^ i
r\:^\.^_:._:"TrT-' "!L_L___J±i-v! ^\^i^[~rv~~]
„ i "i \^ '^Fi ill' :
T -Ts,mTF\ ^ ' i "' 'Vi; i i \
A.
->i
v~v "['"" ^\Y\ ,"1 .i T''"""-t —p——»__
,1
T~~
and clay range
I
+I
100.00 10.00 Millimctcrs |I.OU 0.10 0.01
In addition to gradation, the sand material comprising the engineered material was highly angularfrom the crushing
operations at the quarry, which provided the structural benefit of being able to stand at a 45° angle to nearly vertical
angle when placed,
As noted earlier, DENR in its letter to EPA stated, "the engineered material serves as a man-made conduit to surface
water. "The use of the term "conduit" can be interpreted as a pipe or conveyance device with abnormal and excessive
flow values as compared to soil, A more accurate means in describing any material would be the determination of
the hydraulic conductivity characteristics of the material, which in this case is "fine to coarse grade sand."
Hydraulic conductivity is a measure of a material's capacity to transmit water, It is defined as a constant of
proportionality relating the specific discharge of a porous medium under a unit hydraulic gradient in Darcy's law
which is defined by the equation,
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V = -K I, where V is specific discharge [L/T], K is hydraulic conductivity [L/T] and i is hydraulic gradient,
Presented in the following table (source from Domenico, P.A. and F.W. Schwartz, 1990. Physical and Chemical
Hydrogeology, John Wiley & Sons, New York, page 824) is a summary of general ranges of value of hydraulic
conductivity for unconsolidated materials, including fine sand, medium sand, coarse sand, and gravel.
Hydraulic Conductivity - unconsolidated materials (not placed and densified)
Material
Gravel
Coarse sand
Medium sand
Fine sand
m/see range
low
0.0003|
0.00000091
0.00000091
0.00000021
high
0.03
0.006
0.0005
0.0002
ft/sec range
low
0.001]
0.0000031
0.0000031
0.00000071
high
0.1
0.02
0.002
0.00066
Range in time to travel
50 feet (hours)
maximum
14
4,704
4,704
21,167
minimum
0.1
0.7
8.5
21.2
Averaged range in time of fine to coarse
grain sand to travel 50 feet (hours)
maximum
20
10,191
minimum
0.2
10
Gravel was added to the table since the DENR letter to EPA specified it in the engineered material, even though the
ASTM testing classified the material as a fine to coarse grain sand, The yellow highlighted areas relate to the
engineered material. The last two columns represent the average times (maximum and minimum) for MBR treated
water to travel through the engineered material (the combination of fine, medium and coarse grain sand) to reach
the underdrain collection system.
These values of 10,191 hours and 10 hours respectively, for the maximum and minimum times do not take into
account that the engineered material is not in an unconsolidated state, as it is placed in lifts and densified, and
would result in lower hydraulic conductivity values, However, using the minimum value of 10 hours substantiates
that the pathway is not a "conduit" such as a pipe, that directly discharges to surface waters.
It would have been helpful to EPA had EPA been made aware of the ASTM classification of the non-native material
("engineered material"). In addition to the non-native material ("engineered material"), Pluris evaluated other "native"
material in the area, commonly known as Newhan sand, which is prevalent inland, in the southeast coastal areas of
North Carolina. The ASTM D-422 gradation analysis results of native Newhan sand was also a fine to coarse grain
sand, as with the non-native engineered material, but does not have near the angularity of the engineered material.
In a meeting between DENR and Pluris with then Assistant Secretary of the North Carolina Department
of Environment, Mitehell Gillespie, native Newhan sand would likely not have been an issue, had the DENR reviewed
the ASTM D-422 results of both the non-native materials with native Newhan sand.
The point being, that had Newhan sand ("native material") been present in the high rate infiltration basin berms, the
DENR would not have concluded that the "native material" was a conduit to surface waters, even though the native
and non-native engineered materials shared the same ASTM classification as a fine to coarse grain sand, having
no gravel, much less any cobbles.
Although not native, the engineered material was placed in accordance with ASTM protocols. This included 6-8 inch
horizontal layers or "lifts" and each lift compacted to between 90 and 100 percent maximum density, which on
average would be denser than in place natural Newhan sand native materials,
In addition to physical material testing on the non-native engineered material, biological testing began in 2017 and
would serve as a biological baseline for historical data for future use. Pluris met with Professor Francis L. de los
Reyes III, Ph.D., Department of Civil, Construction, and Environmental Engineering at North Carolina State
University to discuss a study on the non-native sand material.
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In wastewater treatment plants, sand filters have been used for over 100 years in the treatment design ^'Wastewater
Engineering Treatment and Disposal", page 561, Metcalf and Eddy, second edition"). The question in advanced
membrane bioreactor treatment using non-native (engineered) materials is,
"Can microbial colonies form on the sand particles comprising the non-native materials and
encourage microbial activity in low velocity infiltration conditions, to offer continued treatment
following MBR treatment, prior to discharge into low flow/zero flow as well as surface waters?"
The non-native material berm measures 100 feet wide at the water line in each of the two adjacent high rate
infiltration ("HRI") basins with 50 feet of horizontal distance separating the center berm underdrain from the nearest
point of MBR treated effluent water. It should be noted that although drinking water sand filters are predominantly
comprised of fine grain sand, drinking water sand filters are on the order of less than 5 feet in length, The horizontal
column thickness in the HRI basins is in excess of 50 feet.
Pluris provided Dr. de los Reyes' Department at NC State University a grant to conduct a multi-month study, resulting
in its February 8, 2017 technical report, "Metagenomic and Metatranscriptomic Analysis of High Rate Infiltration
Basin Samples to Assess Microbial Activity", prepared by Francis L, de los Reyes III, Ph.D., and Xia He, Ph.D, A
copy of the report is attached to the email with this letter.
An excerpt from the reports states,
"Analysis of the dominant species within the berm showed the presence of Nitrosopumilus maritimus, Nevskia
ramose, Candidatus Scalindua brodae and Pseudomonas plecoglossicida, providing evidence for potential nitrogen
removal from wastewater via filtration, ammonia oxidation and uptake, nitrate reduction, and anaerobic ammonium
oxidation. The detection of Runella limosa weakly suggests that phosphorous removal may occur within the
engineered berm. The combined results show that microorganisms can grow on the filtration medium and may
metabolize the residual constituents such as nitrogen and phosphorus in the effluent from the membrane bioreactor."
Dr. de los Reyes and his Department will be providing Pluris with an additional comprehensive study on the non-
native materials within the high rate infiltration ponds at Pluris Hampstead and Pluris has provided a grant to his
department at NC State for this investigation, The study will be a multi-month analysis and Pluris believes it will
confirm the prior non-native material study conducted in 2017. Results of this study will be forwarded to the DEQ,
the UNC Chapel Hill Collaboratory and the EPA.
In addition to Dr. de los Reyes, in 2017 Pluris retained a highly respected environmental consulting and modelling
firm, Wetlands Studies and Solutions, Inc. ("WSSI") to review the non-native materials at the site as well as the
DENR and EPA letters. Andrew Kassoff, PE, PG, LEED AP, the Principal Engineer/Scientist for WSSI was the
project manager on the project, WSSI is well known to the EPA. Katie Shoemaker, PE, CFM, Senior Engineer, is
responsible for modeling on Pluris's current NPDES permit application before the DEQ at Hampstead. Unrelated,
on a keynote project, Ms, Shoemaker is currently the project manager on a five year benthic TMDL comprehensive
modeling and consulting contract to the state of Virginia, through an EPA funded grant, on the Chesapeake Bay, the
largest estuary in the U.S. Pluris is confident Katie is qualified to conduct a model leading to the goals of the NPDES
permit.
On the review of the non-native materials, Mr. Kassoff's March 14, 2017 report (attached to the email with this
letter) for Pluris is summarized in the statement on the following page,
"The overriding conclusion of this review is that the engineered sand material in the berm is effectively
providing wastewater treatment. The previous interpretations of the engineered material as serving
as a "conduit" for the conveyance of treated wastewater were, therefore, inaccurate. The engineered
sand material does convey the treated effluent, but at a hydraulic conductivity substantially similar to
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that of a native material. The advantage of the engineered sand material is that it provides a media
for highly uniform microbial growth, and subsequent treatment, throughout the constructed thickness
of the berm. The berm itself, therefore, should be considered an important component of the treatment
train of the WWTP system at this facility."
In addition to Mr, Kassoff's professional opinion, more recent correspondence from Dr. de los Reyes regarding
advanced membrane bio-reactor wastewater treatment in NPDES permitting into low flow/zero flow streams and
impaired wetlands, Dr. de los Reyes, stated,
"In my opinion, the quality of the effluent from these MBRs is very high, and would meet the most stringent effluent
limits on current NPDES permits. Such highly treated wastewater may have ecological benefits. A recent review
showed potential "for these systems to serve as refuges of aquatic biodiversity and corridors of ecological
connectivity when wastewater treatment standards are high..."
Pluris takes no issue with modeling as part of permitting, but it is our professional opinion, as well as many if not
most professionals in the environmental industry, that actual outcome is more important than predictive modeling.
Predicting what might happen can only be confirmed with actual outcomes and this may not be known for several
years later.
Albeit somewhat subjective in observing affects over time, Pluris has installed fishtanks at each of its MBR facilities
following completion and startup. Two of the fishtanks are shown below. The fishtanks serve to monitor ongoing
outcome of aquatic biota over years. MBR treated affluent flows through the fishtanks 24/7/365 and there is no
addition of chemicals into the tanks.
The fishtanks have also served for elementary, middle school and high school field trips to educate students on how
advanced treatment can protect the environment. The fishtank on the left is 14 years old and other than 2 Tilapias
growing too large for the tanks, no fish have died in that tank. The tank on the right is in the Hampstead MBR facility
and is 5 years old and like the other tank, no fish have died in that tank,
Videos of these two fishtanks were presented to both DEQ and EPA staff recently, A comment was made on a
Microsoft Teams meeting by DEQ that, "it is the bubblers that keep the fish alive." It was pointed out on the call that
there were no bubblers in the 14 year old fishtank (left tank).
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In admittedly a less variable environment, the fishtanks show actual outcome, and with strict discharge limits
associated with MBR treatment, Pluris believes recorded outcomes after 14 years of MBR treatment affirms there is
no harm aquatic biota in the actual field.
Shown in the following recent photograph is a screenshot off of a video of the Hampstead high-rate infiltration ("HRI")
basins at Hampstead. The operators were removing a layer of duck weed that was covering the surface of the basins
and in doing so observed goldfish swimming in the HRI basins.
The staff had introduced several male and female goldfish into the fishtank in the control room a couple of years
ago.
MBR treated effluent constantly flows through the fishtank and drains to the wet well that then drains via gravity to
the HRI pond basins.
The male and female goldfish are still in the fishtank, as fish cannot make it through the fishtank, due to drain screens
within the tank. Apparently, fertilized eggs can pass and have made their way out of the fishtank to the HRI pond
basins and goldfish have multiplied over time. There is no possibility for the goldfish to exit the HRI ponds. Only
water can escape and that by infiltration through sidewalls in the basins,
The staff decided to drain the HRI basins to clean out the goldfish and plan to introduce bass into the two basins to
address future goldfish over population and sterile grass carp to consume the duck weed, The operators estimated
there were several hundred goldfish ranging in size from less than 1 inch to 9 inches in length. It is important to note
that DO from the MBR treated effluent is significant, as there is no aeration of the HRI ponds.
I have sent each of you along with the people being copied with this letter a Link, allowing you to view 13 short
videos (approximately 15 seconds each), which show 14 years of history of actual native biota thriving in HRI ponds,
stormwater ponds, and level spreader. The video the above screen shot showing the goldfish in the Hampstead HRI
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basins is also included in that share file, You will receive the invitation following this letter and attachments being
emailed out.
I am inviting you Zachary and Nathaniel to drive down to Hampstead and visit the MBR treatment facility during
construction. You can observe the current plant operations as well as see firsthand the construction in progress of
the new expansion. You would also be able to walk on top of the engineered material and see firsthand what the
material is comprised of.
Our facilities do not focus on appearance but on performance. We focus on utilizing the finest equipment in the
world, including Aerzen blowers from Germany, membranes by Kubota from Japan and logic/scada systems from
Allen-Bradley here in the US.
In conclusion, I hope this letter, along with all of the attachments, at a minimum demonstrates Pluris' commitment to
the environment and that it has not, nor is currently violating the federal Clean Water Act.
Sincerely,
Maurice W, Gallarda, PE
Managing Member
Cc: Julie Gryzb, Deputy Director, Division of Water Resources, DEQ (via email to iulie.grzvb(5)deq.nc.qov)
Michael Montebello, NPDES Permitting Section Chief (via email to michael.montebello(a)deq.nc.gov)
Richard Rogers, Director, Division of Water Resources, DEQ (via email to richard.roqers(%deq.nc.gov)
Craig Hesterlee, Acting Branch Chief, EPA Region 4, (via email to Hesterlee.Craiq(a)epa.Qov)
Daniel Holliman, Chief NPDES Permitting Section, EPA Region 4 (via email to Holliman.Danieltoa.ciov)
Michael Gallant, PE, Design Engineer (via email to [e-mail])
Jeff Warren, Executive Director, NC Policy Collaboratory (via email to ieff.warren(a).unc.edu)
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