The Allan Lindsey Center - SHWT Explanation

Anen, Steven C
From:Luke Bugenske <[e-mail]>
Sent:Wednesday, August 8, 2018 3:55 PM
To:Anen, Steven C
Cc:Greg Welsh
Subject:Re: \[External\] Fwd: The Allan Lindsey Center
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No, I think we talked about this on the phone a few weeks ago. There is 2' of separation between the bottom of
media and top of existing grade. The sand filter is on fill material.

Luke

On Wed, Aug 8, 2018 at 3:51 PM Anen, Steven C <[e-mail]> wrote:
Hi Luke,

Did you submit a geotechnical report to determine the depth to the seasonal high water table? I don’t see one with the
application. It’s required for sand filters to comply with MDC 1 (SHWT Separation).

Corey Anen
Environmental Engineer
North Carolina Department of Environmental Quality
Division of Energy, Mineral & Land Resources Stormwater Program

512 N. Salisbury Street
1612 Mail Service Center
1

Raleigh, NC 27699-1612

919-707-3649
[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.

From: Luke Bugenske \[mailto:[e-mail]\]
Sent: Tuesday, August 7, 2018 9:58 AM
To: Anen, Steven C <[e-mail]>
Cc: Greg Welsh <[e-mail]>
Subject: Re: \[External\] Fwd: The Allan Lindsey Center

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Good morning Corey,

Would you mind giving me an update on the re-review of this project? The Owner is asking when we should
expect feedback from reviewers. If you have any questions or need anything else from us to assist your review
please let me know.

Thanks,
Luke

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On Tue, Jul 17, 2018 at 9:26 AM Luke Bugenske <[e-mail]> wrote:
10-4, thanks Corey.

Luke

On Tue, Jul 17, 2018 at 9:25 AM Anen, Steven C <[e-mail]> wrote:
Hi Luke,

Sorry for the delayed response. I’ve been sick and out of the office for a while. I discussed this further with a couple
of coworkers. They told me that we have let people use the formula from the old BMP Manual for sizing sand filters. I
haven’t been in the program for very long and I was unaware. The 315 sf sand layer is acceptable. I apologize for the
confusion.

Let me know if you need any more information.

Thanks,

Corey Anen
Environmental Engineer
3

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

919-807-6378
[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.

From: Luke Bugenske \[mailto:[e-mail]\]
Sent: Monday, July 16, 2018 12:55 PM
To: Anen, Steven C <[e-mail]>
Cc: Greg Welsh <[e-mail]>
Subject: Re: \[External\] Fwd: The Allan Lindsey Center

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Corey,

Can you let me know how we should proceed on this?

Thanks,
Luke

4

On Wed, Jul 11, 2018 at 11:56 AM Luke Bugenske <[e-mail]> wrote:
Corey,

Thanks for taking the time to talk through this. The water quality volume for this project is 4,670-cf,
adjusted to 3,503-cf (WQVadj). There is 4.5' of storage between the top of media and top of outlet structure
(spillway). If half of the WQVadj needs to be stored over the filter media, the top of the media would need
to be 389.22-sf. This is different than the number we get using the formula in the BMP manual. The
equation calculates an area of 264-sf will drain the WQVadj in 40 hours (see page 1 of the attachment). We
provided 315-sf.

We can increase the filter media to 389.22-sf if it is required. Please review and advise.

Thanks,
Luke

On Wed, Jul 11, 2018 at 11:16 AM Anen, Steven C <[e-mail]> wrote:
Greg,
5

The requirement to have equivalent volumes in the sand and sediment chambers does apply to above ground
systems, but is specific to the water quality volume. The system has to be designed so that half of the water quality
volume can be stored above the sand. Additional storage space can be provided for larger storm events. The extra
storage space does not have to have a sand bottom.

Corey Anen
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

919-807-6378
[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.

From: Greg Welsh \[mailto:[e-mail]\]
Sent: Monday, July 9, 2018 10:31 AM
To: Anen, Steven C <[e-mail]>
Cc: Luke Bugenske <[e-mail]>
Subject: Re: \[External\] Fwd: The Allan Lindsey Center

6

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Steven,

Not to be argumentative but just trying to get clarification on this. Like Luke said, we've done dozens of
sand filter designs around the state where we've oversized the forebay to get detention to work. Also, we
limit the size of the sand filter footprint to attenuate the smaller storm events. Having too much
sandfilter/underdrain puts us out of compliance for peak discharge on the 1 and 2-year events.

Here's a screen shot of a project we permitted just last week through the NCDEQ (approval attached). I
realize the chamber details make it appear (and clearly state) that the forebay and sandfilter chamber
should have equivalent volumes but I think the detail applies to chamber systems only. For above-ground
systems, the DEQ has allowed us to oversize the forebay on numerous occasions. We'd love a second
opinion on this if you wouldn't mind.

Please feel free to call me to discuss [phone].

Thanks.

Greg

On Mon, Jul 9, 2018 at 10:04 AM, Anen, Steven C <[e-mail]> wrote:
7

Luke,

Sand Filter MDC 2 requires a two chamber system, with a sediment chamber and a sand chamber with the storage
in both chambers being equivalent. Note that the diagram on Page 2 of the sand filter chapter states that the
“minimum combined volume of sediment chamber and storage above sand filter media is 0.75 times the
treatment volume.” The intention is for the entire area that is being used to treat the water quality volume to be
sand, as is shown in all of the diagrams of the chapter.

Corey Anen
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

919-807-6378
[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.

From: Luke Bugenske \[mailto:[e-mail]\]
Sent: Friday, July 6, 2018 3:35 PM
To: Anen, Steven C <[e-mail]>
Cc: Greg Welsh <[e-mail]>
Subject: \[External\] Fwd: The Allan Lindsey Center

8

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Corey,

Regarding comment #5 ("The entire bed of the sand chamber must contain the sand filter media"), this is
not a requirement that I see in the Sand Filter MDC. We have done several sand filter designs where
throughout the state where this is not required. Please let me know where this requirement is coming
from.

Thanks,
Luke

---------- Forwarded message ---------
From: Greg Welsh <[e-mail]>
Date: Thu, Jun 14, 2018 at 5:59 PM
Subject: Fwd: The Allan Lindsey Center
To: Luke Bugenske <[e-mail]>, Eleanor Thomas <[e-mail]>

Begin forwarded message:
From: "Anen, Steven C" <[e-mail]>
Date: June 14, 2018 at 5:56:29 PM EDT
To: "[e-mail]" <[e-mail]>
Cc: "Khan, Zahid" <[e-mail]>, "[e-mail]"
<[e-mail]>
Subject: The Allan Lindsey Center
Good afternoon,

The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on June 6, 2018. 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.

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Thank you,

Corey Anen
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

919-807-6378
[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.

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