SW5210304_Emails_20210615

Farkas, Jim J
From:Farkas, Jim J
Sent:Tuesday, June 15, 2021 4:14 PM
To:Dan Withers
Subject:RE: \[External\] RE: Youngsville Storage
Dan,

I was looking over the additional information you provided on 6/9/2021. Everything looks good except for a few small
issues:

Please correct the following:
- Prior Comment 6 – Please provide original signed hard copies of the Supplement-EZ Form & calculations
(Originals of these items were provided on 6/2/2021, however due to these and prior comments, these
items are no longer “up-to-date” and need to be replaced).
- Prior Comment 12 – I did not see riprap calculations for the inlets and outlets of the proposed SCMs in the
provided calculation booklets. Please ensure that calculations, in accordance with General MDC 4, are
included in the submission. It is noted that the riprap apron sizing is shown on plan sheet C-7.2, however
calculations showing how these values were determined need to be included in the calculation package.
- Infiltration MDC 2 – The lowest point of the infiltration system must be a minimum of two feet above the
SHWT. Both infiltration basins have forebays that are too close to the SHWT (SCM #1’s forebay only has a
foot of separation from the SHWT and SCM #2’s forebay intercepts the SHWT). Unlike other SCMs, there are
no minimum size requirements or design guidance for infiltration basin forebays so you have some flexibility
in designing/sizing the forebays (You can also use a different pretreatment method as outlined in Infiltration
MDC 4). Please revise the design and update the Supplement-EZ Form as needed so that all applicable
design requirements are met.
- Infiltration MDC 5 – Using the given design information in the Supplement-EZ Form (Factor of Safety = 2.0,
Design Volume = 10,814 cf, k = 0.5 in/hr, & Surface Area = 6,429 sf), SCM #2 does not drawdown within the
stipulated 72 hour timeframe. Please revise the design and update the Supplement-EZ Form as needed so
that all applicable design requirements are met. As mentioned in an earlier email, please also correct the soil
infiltration rate used in the calculations for this SCM.
- Supplement-EZ Form, Infiltration System Page, SCM #1, Line 22 & 24 – The SHWT elevation shown here
(465.50) does not match the SHWT as indicated on the plans (456.50). Please revise the design and/or
update the Supplement-EZ Form as needed for consistency/compliance with all applicable design
requirements.

Please provide the following:
- 1x signed hard copy & 1x electronic copy of the revised Supplement-EZ Form & calculations
- 2x hard copies & 1x electronic copy of any revised plan sheets
- Hard copies of any items electronically provided on 6/9/2021 that are not being revised as part of this round
of comments
- Any other items that need to be updated in order to address these comments

Hard copies should be mailed to me at the following address:
- For FedEx/UPS:
Suzanne McCoy
512 N. Salisbury Street, Office 640K
Raleigh, NC 27604

1

- For USPS:
Suzanne McCoy
1612 Mail Service Center
Raleigh, NC 27699-1612

Electronic copies should be uploaded at the following location:
https://edocs.deq.nc.gov/Forms/SW-Supplemental-Upload

Since these are really minor things, once I get the hard copies, anything else that may have changed from addressing
these issues, and the documents are uploaded to Laserfiche (Provided everything is still in order), we can issue the
permit without doing a formal 30-45 day review.

Let me know if you have any questions.

Jim Farkas
Environmental Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral, & Land Resources – Stormwater Program

512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612

[phone]
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

Based on the current guidance to minimize the spread of COVID-19, the Department of Environmental Quality has
adjusted operations to protect the health and safety of the staff and public. Many employees are working remotely or
are on staggered shifts. To accommodate these staffing changes, all DEQ office locations are limiting public access to
appointments only. Please check with the appropriate staff before visiting our offices, as we may be able to handle your
requests by phone or email. We appreciate your patience as we continue to serve the public during this challenging
time.

From: Dan Withers <[e-mail]>
Sent: Tuesday, June 15, 2021 12:25 PM
To: Farkas, Jim J <[e-mail]>
Subject: Re: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to
Report Spam.
2

I think you’re right - SCM 2 has a bit of wiggle room so I can just adjust the invert of the overflow pipe to get the volume
right. Looking forward to the rest of your comments. Thanks so much for your patience and helpfulness on this project.

Dan Withers, PE
Project Manager

Ark Consulting Group, pllc
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without reading, printing, copying or forwarding it.
Please let us know of the error immediately so that we can prevent it from happening again. You may reply directly to the sender of this message.
Neither the name of Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group, PLLC, shall be
considered an electronic signature unless specifically stated otherwise in this email. Thank you.

On Jun 15, 2021, at 11:29, Farkas, Jim J <[e-mail]> wrote:

The 2.0 factor of safety isn’t a codified requirement (i.e., I can’t legally make you use a 2.0 factor of
safety), it’s more of a “best professional practice” (kind of like selecting a Manning’s roughness
coefficient. We provide values that we are comfortable with, but we do not limit engineers to only using
the values we provide). If you, using your best professional judgement, believe that a less conservative
factor of safety (provided that the MDC is still met) would be appropriate in this situation, you can do
that (although we strongly recommend against doing that since there is a certain inherent uncertainty in
soil testing and, as the infiltration basin ages, the infiltration rate diminishes (possibly leaving the owner
with a non-compliant SCM)). If you plan on doing this, we would ask that you provide a
justification/explanation for your deviation.

For this particular situation, it’s not that hard of an issue to overcome. You could reduce the design
storage volume (by lowering the overflow pipe) that this SCM provides from 10,814 cf to 9,640-ish cf
(you could probably even reduce it to a lower amount if you so choose). The runoff volume matching
should still work out (since the SCM is oversized) and the drawdown calculations should work out (since
the bottom surface area isn’t changing, but the design volume is being decreased). I’m still reviewing the
submission so hold off on any redesigns for now. I should have something back to you soon.

-Jim

From: Dan Withers <[e-mail]>
Sent: Tuesday, June 15, 2021 10:48 AM
To: Farkas, Jim J <[e-mail]>
Subject: Re: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an
attachment to Report Spam.

It may have been a typo or a holdover from a previous design. I also see 0.5 on the second to last page
of the appendices in the narrative. Unfortunately 0.5 kicks the drawdown time to 81 hours at the
preferred safety factor, so I may need to tweak that SCM to get back to <72 unless we can deviate
slightly from 2.0 SF.
3

Dan Withers, PE
Project Manager

Ark Consulting Group, pllc
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without reading, printing, copying
or forwarding it. Please let us know of the error immediately so that we can prevent it from happening again. You may reply
directly to the sender of this message. Neither the name of Ark Consulting Group, PLLC or its representative, nor transmission
of this email from Ark Consulting Group, PLLC, shall be considered an electronic signature unless specifically stated otherwise in
this email. Thank you.

On Jun 15, 2021, at 10:13, Farkas, Jim J <[e-mail]> wrote:

Quick question,

The hydraulic conductivity of the soil for Infiltration Basin 2 is shown as 0.57 in/hr in the
drawdown calculations. Where did this number come from? The soils reports seem to
indicate that the soil infiltration rate is 0.5 in/hr.

Thanks,

-Jim

From: Dan Withers <[e-mail]>
Sent: Wednesday, June 9, 2021 9:51 AM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Good morning, Jim:

Please see attached updated Application, Supplement, Narrative/Calcs, and Plans. I
attempted to upload these to the “SW_Project_Submittal” link, but was not able today
for some reason. Please let me know if email is acceptable or if there’s some error on
my end. I’ve got hard copies ready to ship as soon as I receive your go-ahead.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

4

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Tuesday, June 8, 2021 8:58 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Yeah, since you are using RVM, you don’t need to provide nutrient calcs.

-Jim

From: Dan Withers <[e-mail]>
Sent: Monday, June 7, 2021 4:43 PM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Thanks for confirming, Jim.

On another note, a colleague asked a question about how runoff volume match affected
nutrient offset strategies and it got me digging into the rules. Am I reading correctly in
15A NCAC 02B .0711(5)(a) and .0731(e)(1) that projects meeting runoff volume match
have satisfied the nutrient management requirements? If so, I plan to omit the nutrient
calculations from my next narrative update.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Monday, June 7, 2021 3:53 PM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Dan,

5

Do the revisions to the calculations/Application/forms/etc… and send me the PDFs
when complete. I’ll review the PDFs. If everything is in order, you can mail in the hard
copies (I can issue the permit while waiting for the hard copies to arrive. I’ll just hold off
on sending the hard copy of the permit to the Applicant until I receive the hard copies
from you).

Let me know if you have any questions,

-Jim

From: Farkas, Jim J
Sent: Friday, June 4, 2021 3:30 PM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

I’ll take a look at the submission on Monday and let you know.

From: Dan Withers <[e-mail]>
Sent: Wednesday, June 2, 2021 2:54 PM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Jim, now that I’ve had a chance to review in detail, I see where the discrepancy lies. The
BUA values shown in the Application and Supplement appear to be accurate and
verifiable with the Drainage Area Map. Unfortunately, the BUA values in the volume
match calculations did not get updated to match. The update necessitates relatively
minor changes to Infiltration Basin #1, which would change the Supplement, design
drawings, and calculations.

What’s the simplest way to get the revisions to you? Should I wait until you’ve
completed your review and prepare a complete response? Should I send you revised
files electronically and mail the final hard copies after you’ve had a chance to
review? Let me know what works best for you.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

6

From: Farkas, Jim J <[e-mail]>
Sent: Wednesday, June 2, 2021 10:53 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Dan,

I was taking a look at the information for this project that was uploaded to Laserfiche on
th
May 28 and I was having a hard time verifying the post-development BUA for the
Neuse portion of the project.

Per the calculations, the post-development BUA for Neuse portion of this project is
100,544 sf (58,750 sf of which is listed as roof and the other 41,794 sf is listed as
transportation).

The Application, Supplement-EZ Form, and plans show the post-development BUA for
Drainage Area 1 (to Infiltration Basin 1) as 83,832 sf (42,285 sf of which is listed as roof
and the other 41,547 sf is listed as parking/existing) and the post-construction BUA for
Drainage Area 2 (Bypass) as 34,470 sf (16,475 sf of which is listed as roof and the other
17,995 sf is listed as street/parking/sidewalk). Adding these two numbers together
results in a total post-development BUA for the Neuse portion of the project as 118,302
sf.

Let me know if I’m missing something.

Jim Farkas
Environmental Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral, & Land Resources – Stormwater Program

512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612

[phone]
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

Based on the current guidance to minimize the spread of COVID-19, the Department of
Environmental Quality has adjusted operations to protect the health and safety of the
staff and public. Many employees are working remotely or are on staggered shifts. To
accommodate these staffing changes, all DEQ office locations are limiting public access
to appointments only. Please check with the appropriate staff before visiting our offices,
7

as we may be able to handle your requests by phone or email. We appreciate your
patience as we continue to serve the public during this challenging time.

From: Farkas, Jim J
Sent: Thursday, May 20, 2021 2:10 PM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Dan,

The calculations look really good (we shouldn’t have any problem approving this
project). I’ll see you tomorrow at 8:30.

-Jim

From: Dan Withers <[e-mail]>
Sent: Thursday, May 20, 2021 12:31 PM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

I’d love to do it this afternoon, but I want you to be able to review the calculations
beforehand and I have a dentist appointment with my children this afternoon. Let’s
shoot for 8:30 tomorrow morning and if you need a different time let me know.

Attached are the following for your review:
 Updated PDF of the Drainage Area Map and SCM sheets
 Infiltration/Annual Runoff Calculation spreadsheet
 Tar-Pamlico Nutrient spreadsheet
 Neuse Nutrient spreadsheet

I’ll send the Teams invite separately.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

8

From: Farkas, Jim J <[e-mail]>
Sent: Thursday, May 20, 2021 10:03 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Absolutely (we use Teams). I’m free any time today (except from 1:00-2:00), tomorrow
morning, or any time next week (Tuesday through Friday). I’d appreciate it if you send
me a copy of the calculations beforehand so that I can look them over prior to our
meeting.

-Jim

From: Dan Withers <[e-mail]>
Sent: Wednesday, May 19, 2021 11:19 AM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Good morning Jim,

Would you consider a web conference (MS Teams, WebEx, Zoom, etc.) to review our
updated calculations before we resubmit? I know the owner is anxious to get started,
so I’d like to try to address all of your comments prior to resubmitting if at all
possible. Please let me know if that’s possible and, if so, what your preferred platform is
and when you’re available.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Tuesday, May 18, 2021 8:41 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Dan,

Sorry for not getting back to you sooner.

9

1) The drawdown rate should be based on the provided water quality volume, not
necessarily the 100% design volume. For example, if the 100% sized design
volume is 1,000 cf and the provided water quality volume is 1,500 cf (150%
sized), the provided water quality volume (1,500 cf) would be used to determine
the drawdown rate and any other applicable MDCs.
2) Sort of. This project straddles the Neuse and the Tar-Pam watershed divide line.
The portions of the project that ultimately drain to the Neuse River should meet
Runoff Volume Matching by themselves and the portions of the project that
ultimately drain to the Tar River should meet Runoff Volume Matching by
themselves (We just want to make sure that neither watershed is adversely
impacted by the proposed development).

Let me know if you have any other questions.

-Jim

From: Dan Withers <[e-mail]>
Sent: Monday, May 17, 2021 3:29 PM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Jim, just wanted to follow up. Have you had a chance to consider my two questions
below?

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Dan Withers
Sent: Monday, May 10, 2021 3:48 PM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Thanks for the thorough response. I followed your methodology assuming that we omit
Infiltration Basin #2 (the smallest and least favorable grading-wise) and found that with
the two larger basins we’re meeting runoff volume match:
 Pre-Development Runoff 248390 cf
 Post-Development Runoff 621732 cf
 Minimum Runoff Reduction Volume 373341 cf
10

 Basin 1 Volume Treated 186783 cf
 Basin 3 Volume Treated 256762 cf

I do have a couple questions left over though. First, when oversizing an infiltration SCM,
does the drawdown time have to be met for a 100% design volume storm, or does it
have to be met for the full as-designed volume of the SCM?

Second, are you suggesting in your commentary below that I need to run individual
runoff volume match calculations for each basin? In other words, the Tar-Pamlico side
of the project must meet runoff volume match on its own? An likewise for the Neuse
side?

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Thursday, May 6, 2021 11:47 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

The main advantage of using Runoff Volume Matching is that you do not need to
capture/treat all of the new BUA in SCMs like you do with Runoff Treatment (You just
need to manage the annual runoff volume).

Just based on some quick calculations for this project, it looks like you could remove
infiltration basin #1 or #2 or reduce the size of the infiltration basins and still meet
Runoff Volume Matching (based on the information provided in the submission
package).

We’ll assume that…
P = 45.76 in
Project Area = 377,230 sf
On-site BUA in Pre-development Conditions = 51,836 sf (13.7% impervious, Rv = 0.174)
On-site BUA in Post-development Conditions = 173,369 sf (net increase of 121,533 sf,
46% impervious, Rv = 0.464)

Pre-development ARV = 0.9 * 0.174 * 377,230 sf * (46.76 in / 12) = 224,845 cf
Post-development ARV (without SCMs) = 0.9 * 0.464 * 377,230 sf * (46.76 in / 12) =
600,234 cf
Minimum Runoff Reduction Volume that needs to be provided = 600,234 cf – 110% *
224,845 cf = 352,905 cf

11

Infiltration Basin 1:
- 100% Sized Design Volume = 4,801 cf (DA = 88,458 sf, IA = 59,105 sf, Rv = 0.67,
DV = (1.0”/12) * 0.67 * 88,458 sf)
- Treatment Volume Provided = 12,750 cf (>200% sized, so assume that 200%
sized for calculations)
- Runoff Reduction Volume provided from SCM = 193,432 cf

Infiltration Basin 2:
- 100% Sized Design Volume = 2,038 cf (DA = 32,770 sf, IA = 25,352 sf, Rv = 0.75)
- Treatment Volume Provided = 5,030 cf (>200% sized, so assume that 200% sized
for calculations)
- Runoff Reduction Volume provided from SCM = 82,101 cf

Infiltration Basin 3:
- 100% Sized Design Volume = 7,123 cf (DA = 150,264 sf, IA = 86,626 sf, Rv = 0.57)
- Treatment Volume Provided = 10,089 cf (141.6% sized)
- Runoff Reduction Volume provided from SCM = 275,119 cf

Total Runoff Reduction Volume provided = 550,652 cf (550,652 cf = 193,432 cf + 82,101
cf + 275,119 cf)
Post-development ARV (with SCMs) = 0.9 * 0.464 * 377,230 sf * (46.76 in / 12) –
550,652cf = 49,582 cf

Since the post-development ARV (49,582 cf) does not increase by more than 10% from
the pre-development ARV (224,845 cf), Runoff Volume Matching has been met. This
configuration reduces the post-development ARV below the existing conditions (which
is above and beyond the requirements). The amount of provided treatment could be
reduced (by removing infiltration basin #1 or #2 or reducing the sizes of the infiltration
basins) while still meeting Runoff Volume Matching. These calculations may not be
100% accurate (I’m not sure if all of the values used are correct and since the project is
located within two drainage basins, these calculations should be done for the portion of
the project that drains to the Neuse basin and the portion of the project that drains to
the Tar-Pam basin), but they are illustrative of the benefits of using Runoff Volume
Matching (especially if you have oversized infiltration basins over HSG A soils). It’s
ultimately your choice I just wanted to let you know your options.

-Jim

From: Dan Withers <[e-mail]>
Sent: Thursday, May 6, 2021 10:00 AM
To: Farkas, Jim J <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Jim, my biggest question is related to the advantages of going with a runoff volume
match methodology.

I did a quick revision to my calculations yesterday and found that after I corrected my
Discrete NRCS method the three SCM’s previously proposed are still generally about the
12

right size (I had to make a small adjustment to two basins to get more surface area, but
the volumes were sufficient). Doing a quick check on the runoff volume method, it
appears to me that the maximum runoff volume allowed is ~57000 CF, and the current
infiltration design results in a net annual runoff volume of ~94000 CF. That was a really
rough check, but unless there’s another advantage to runoff volume match that I’m
missing, it seems like I need to stick to runoff treatment.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Thursday, May 6, 2021 9:26 AM
To: Dan Withers <[e-mail]>
Subject: RE: \[External\] RE: Youngsville Storage

Dan,

The average annual runoff volume (Used for Runoff Volume Matching) is calculated
using the following formula:

ARV = Pj * Rv * A * (P/12)

Where:

ARV = Annual Runoff Volume (cf)
Pj = Fraction of rainfall events that produce runoff (Assumed to be 0.9)
Rv = Runoff Coefficient = 0.05 + (0.9 * Ia)
Ia = Percent impervious area, expressed as a decimal
A = Area of interest (sf). This would be the project/property area
P = Average annual rainfall amount (in). The “/12” is used to convert to ft. An average
annual rainfall map and station readings can be found in the SNAP Tool spreadsheet:
https://deq.nc.gov/about/divisions/water-resources/planning/nonpoint-source-
management/nutrient-offset-information#stormwater-nutrient-accounting-tools or in
the attached draft document.

Calculate the ARV for existing conditions and for proposed conditions (Proposed
conditions are calculated assuming no impact from SCMs and then a volume reduction
amount is subtracted to get the “actual” ARV for proposed conditions. See attached
draft document). The volume reduction amount is calculated based on information in
the SCM Credit Document:
https://files.nc.gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwat
13

er/BMP%20Manual/SCM-Credit-Doc-2018-11-7.pdf If the increase from existing to
proposed conditions is less than 10%, the project meets Runoff Volume Matching.

We currently don’t have any published guidance on this (I’ve attached a draft copy of
the guidance that we will be publishing in the near future, it goes into more depth on
the methodology and has some design examples).

Look over the document and give the calculations a try. If something is unclear or you’re
unsure of something, let me know and we’ll work through it. If you have any other
questions, don’t hesitate to contact me. If this method works out for the project we can
schedule a phone call to go over the calculations and/or what would need to be
submitted.

Jim Farkas
Environmental Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral, & Land Resources – Stormwater Program

512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612

[phone]
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

Based on the current guidance to minimize the spread of COVID-19, the Department of
Environmental Quality has adjusted operations to protect the health and safety of the
staff and public. Many employees are working remotely or are on staggered shifts. To
accommodate these staffing changes, all DEQ office locations are limiting public access
to appointments only. Please check with the appropriate staff before visiting our offices,
as we may be able to handle your requests by phone or email. We appreciate your
patience as we continue to serve the public during this challenging time.

From: Dan Withers <[e-mail]>
Sent: Wednesday, May 5, 2021 5:04 PM
To: Farkas, Jim J <[e-mail]>
Cc: Valentine, Thad <[e-mail]>
Subject: \[External\] RE: Youngsville Storage

14

CAUTION: External email. Do not click links or open attachments unless you verify. Send all
suspicious email as an attachment to Report Spam.

Good afternoon, Jim:

Thanks for sending your comments. I may have further questions as I continue to
address your comments, but the first thing I’m interested in talking to you about is
runoff volume matching for the project. Please let me know when may be convenient,
or feel free to call me anytime on my cell phone – 252.646.2257.

Dan Withers, PE
Project Manager

A RK C ONSULTING G ROUP, PLLC
252.565.1017 (Direct)
252.646.2257 (Mobile)
[e-mail]

If you have received this confidential message in error, please destroy it and any attachments without
reading, printing, copying or forwarding it. Please let us know of the error immediately so that we can
prevent it from happening again. You may reply directly to the sender of this message. Neither the name of
Ark Consulting Group, PLLC or its representative, nor transmission of this email from Ark Consulting Group,
PLLC, shall be considered an electronic signature unless specifically stated otherwise in this email. Thank
you.

From: Farkas, Jim J <[e-mail]>
Sent: Wednesday, May 5, 2021 2:50 PM
To: Dan Withers <[e-mail]>
Cc: Valentine, Thad <[e-mail]>
Subject: Youngsville Storage

Good Afternoon,
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
rd
Management Permit Application for the subject project on March 23, 2021. A review
of that information has determined that the application is not complete. Attached is a
letter describing the items that need to be submitted. If you have any questions, please
feel free to contact me. My contact information is listed below.
Thank you,

Jim Farkas
Environmental Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral, & Land Resources – Stormwater Program

512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612

15

[phone]
[e-mail]

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.

Based on the current guidance to minimize the spread of COVID-19, the Department of
Environmental Quality has adjusted operations to protect the health and safety of the
staff and public. Many employees are working remotely or are on staggered shifts. To
accommodate these staffing changes, all DEQ office locations are limiting public access
to appointments only. Please check with the appropriate staff before visiting our offices,
as we may be able to handle your requests by phone or email. We appreciate your
patience as we continue to serve the public during this challenging time.

16