20060888 Ver 2_Emails_20070703

Re: FW: Holts Lake West Subdivision -NCDWQ Comments
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Subject: Re: FW: Holts Lake West Subdivision -NCDWQ Comments
From: Annette Lucas <[e-mail]>
Date: Tue, 03 Jul 2007 09:35:28 -0400
To: BRL Engineering <[e-mail]>
CC: [e-mail], [e-mail],'Will Moore' <[e-mail]>
Dear Brian:
I did provide comments 3 and 4 on the Request for More Information Letter for Holts
Lake Subdivision 06-0888v2:
3. Drainage ditches:
Please number the drainage ditches on the Site Plan and Overall Subdivision Layout
Sheet (SP-1). It is very difficult for the DWQ to match the calculations with the
appropriate drainage ditch.
Please provide clearly labeled cross-sectional details of each of the proposed
drainage ditches as well as velocity calculations. In order to discharge to the
wetlands, a non-erosive velocity of less than 2.0 feet per second during the 10-year,
24-hour storm must be established. Please provide all the calculations needed to
demonstrate that an appropriate velocity has been established at every proposed
outfall to wetlands. Please clearly label each set of calculations so that the DWQ
can easily match the calculations with the ditch to which they apply.
4. Diffuse flow to riparian buffers:
Please show how diffuse flow has been established to riparian buffers on this
project. Per 15A NCAC 2B .0233, concentrated flow from the road, driveways and
rooftops must be converted to diffuse flow before it is allowed to discharge through
the riparian buffer. If one or more level spreaders is proposed, please provide a DWQ
Level Spreader Worksheet (available on the 401 web site) for each one as well as all
of the Required Items listed in the worksheet.
Brian, as you know I review a lot of projects and if the information is not easily
accessible, I request it to be organized in a manner that facilitates the review
process. I did take some time with your plans and calculations to decipher which
calculations went with which outlet and was not able to accomplish this in a
time-efficient manner based on the information provided. It is absolutely necessary
that you label the devices on the plans - if the drawing is cluttered, you may need
to provide sheets at a larger scale so that all of the necessary information can be
included. Nearly all the plans I review show BMPs and outlets of interest with
numbers or labels for easy reference. Also, as I stated, I do need to see the
calculations that demonstrate that nonerosive velocities have been achieved in every
ditch.
As for comment 4, I need to see details of every outlet to to determine if Riparian
Buffer rules requirements are being met. This is my responsibility as the reviewer.
Based on your submittal, I was not able to do this, particularly on the lots adjacent
to the riparian buffer on the north side of the project adjacent to Holts Lake. These
lots are likely to have large footprints and that will require one or more engineered
diffuse flow measures to meet buffer rule requirements. The proper design for these
measures needs to be provided at this point in the review process, not later when
then lots are developed.
Sincerely,
Annette
BRL Engineering wrote:
I Hi Annette,
1 of 3 7/3/2007 9:36 AM

Re: FW: Holts Lake West Subdivision -NCDWQ Comments
Not trying to bug you, I know you are busy and of course there is a holiday
tomorrow. But I just wanted to check if you have had a chance to consider my
comments below. We are under a deadline by your office to have the requested info
re-submitted and I want to be sure we address the comments appropriately and
timely. Thanks again for your consideration.
-----Original Message-----
*From:* BRL Engineering [mailto:brlengineering~~~earthlink.net]
*Sent:* Tuesday, June 26, 2007 12:21 PM
*To:* 'Annette Lucas'
*CC:* 'laT:.CTICiTiilla7;~~T'iC?T:all.. ,c t'' 'rifaSSOCiates~~bellsOUth.riet'; 'Will Moore'
*Subject:* Holts Lake West Subdivision - NCDWQ Comments
Hi Annette,
I have received a copy of NCDWQ letter dated 6/18/07 requesting additional
information for DWQ Project # 06-0888, Ver. 2. I received my copy from our
environmental specialist, Mr. Neal Floyd who submitted our PCN. There were 4
comments in that letter and just yesterday I spoke to Mr. Ian McMillan (of your
office) about them. In our conversation it appeared that Comments 3 & 4 most
likely were generated by you and he suggested that I touch base with you on them.
(We also discussed Comments 1 & 2 but I think I will probably let Neal Floyd
coordinate the response for those items since he has been working closely with the
Corps of Engineers on our wetlands impacts).
Regarding Comment 3: I can indeed try to show the Outlet Ditch Numbers on Sheet
SP-1; however, it will clutter that drawing and isn't really consistent with the
property layout, overall lot layout and general notes of that sheet. If it will
help your review I will certainly try to do this; but you may not have noticed the
following... The Outlet Ditch Numbers were shown on Sheets SSD-1 and SSD-2. There
were 5 total outlet ditches and each ditch was numbered in bold within a circle as
being 1/5, 2/5, and so on up to ditch 5/5. The hydrologic calculations (page 91 in
Calcs) and hydraulic calculations (pages 93 and 94 of Calcs) for each of these
ditches match the ditch numbers on the plans (although you will notice in the
talcs that I did have to renumber the ditches to make the numbers match). Also,
each ditch has a detail shown on each of sheets SSD-1 and SSD-2 specifying a
specific ditch shape, depth, lining, etc. If this doesn't help please let me know
and I will do whatever is needed. ---- Regarding the second part of Comment 3: We
did indeed design each outlet ditch that discharges to the wetlands so that
10-year velocities are below 2.0 ft/sec. This criteria is certainly consistent
with a pre-submittal meeting and subsequent telephone conversation that you and I
had before we ever submitted our plan; and you had given us the option of using
utilizing the low velocity criteria or level spreaders before discharging to
wetlands. As I had indicated back then, we chose to design the outlet ditches with
low velocities. I will draw your attention again to pages 93 & 94 of my Calcs. The
2.0 ft/sec was the governing criteria for each outlet ditch that discharges to the
wetlands (note that ditch 4/5 is the only ditch that does not discharge to
wetlands, so the low velocity criteria would not apply to this ditch). However,
you will note in the talcs that due to topography some ditches were split into
upper, middle, and end portions. For these ditches, each "end portion" was
designed to meet the low velocity criteria prior to discharging. I hope that this
is sufficient to clarify and/or satisfy your concerns regarding Comment 3. Please
let me know if it is not.
Regarding Comment 4: I think this comment is explained quite simply in that we are
not proposing any construction impacts to, or proposing any concentrated flow
through, any riparian buffer on this site. You will note from Comment 3 that each
of our outlet ditches, while maybe discharging to wetlands, they do not discharge
to, or through, riparian buffers. As with all subdivision projects, for individual
homesites with riparian buffers it will be up to the individual homeowners to
follow the Rules on their private properties. But any construction associated with
the subdivision itself will promote sheet flow at, or near, any riparian buffers.
Annette, please consider the above clarifications and let me know if they have
satisfied the concerns for Comments 3 & 4. If so, I will insert these responses
2 of 3 7/3/2007 9:36 AM

Re: FW: Holts Lake West Subdivision - NCDWQ Comments
into Neal Floyd's overall response letter to NCDWQ. And hopefully this will get us
on our way to approval! Thank you for your assistance!
Brian R. Leonard, PE, PLS
*BRL ENGINEERING*
704-B East Stanley Street
Four Oaks, NC 27524
919 963-2608
brlenc~ineerir_g:~earthl ink .net
Annette Lucas <a~lnette.lucas~%ncznal.net>
Environmental Engineer III
401 Wetlands Oversight/Express Unit
NC Division of Water Quality
3 of 3 7/3/2007 9:36 AM