HomeMy WebLinkAboutWPO201700070 Other 2019-10-17 (2)CUI
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COUNTY OF ALBEMARLE
Facilities and Environmental Services
Facilities Planning & Construction
Memorandum
TO: Frank Pohl - County Engineer
FROM: Jack Kelsey, PE - Transportation Engineer
DATE: 10 Oct 2019
SUBJECT: WPO-2017-00070 Albemarle County Rte 250 Business (Ivy Road) Sidewalk
The plans and supporting documents included in this resubmittal are provided to specifically address
the previous comments Section — C, comments #3 and #5, through the alternate stormwater
management design discussed in our conference call/meeting with Kimly-Horn on 13 May 2019, and
reviewed and concurred in concept on 6 June 2019 (copy of email enclosed). The few remaining
items will be addressed in the final plan resubmittal.
Please let me know if you have any questions.
Enc.
From: Jack Kelsev
To: Frank Pohl; Mitchell, Michael
Cc: John Anderson; Brian McPeters; Oliver. Jonathan
Subject: RE: Ivy Road Sidewalk - SWM Detention Alternative near Stillfried Lane
Date: Thursday, June 6, 2019 10:17:00 AM
Yes. I went out there during one particular heavy rain and observed water going into the inlet at a
fairly good rate and water flowing out via the 10" pipe at a matching rate. I could see the general
direction of the outflow (NNW) towards the ditch on the north side of Ivy Road. The ditch was full of
water and couldn't locate the outlet end of the pipe and so presumed it was submerged.
.lark II. Eelsor, PE
9'raiisporl3tion Engineer - Earilitirs Plamiiiw k fmislrnrtion EII 3-46
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From: Frank Pohl
Sent: Thursday, June 06, 2019 10:07 AM
To: Mitchell, Michael <Michael.Mitchellna kimley-horn.com>; Jack Kelsey <ikelsey2Palbemarle.org>
Cc: John Anderson <1anderson2(@albemarle.org>; Brian McPeters <l rian.mcpeters(@kimley-
horn.com>; Oliver, Jonathan <Jonathan.Oliver(@kimle)t-horn.com>
Subject: RE: Ivy Road Sidewalk - SWM Detention Alternative near Stillfried Lane
Jack,
It appears this should work. Question, have you or someone confirmed the existing 10-inch pipe is
functioning?
Thanks,
Frank
Frank V. Pohl, PE, CFM
County Engineer
401 McIntire Road
Charlottesville, VA 22902
434-296-5832 (ext. 7914)
From: Mitchell, Michael <Michael.Mitchell(@kimley-horn.com>
Sent: Wednesday, June 5, 2019 6:04 PM
To: Jack Kelsey <ikelsey2Cq)albemarle.org>
Cc: John Anderson <ianderson2(@albemarle.org>; Frank Pohl <foohl(@albemarle.org>; Brian
McPeters <brian.mcpetersPkimley-horn.com>; Oliver, Jonathan <Jonathan.0liverf kimlev-
horn.com>
Subject: Ivy Road Sidewalk - SWM Detention Alternative near Stillfried Lane
Jack,
Following up on the conference call regarding the Ivy Road SWM design from a few weeks ago:
We have analyzed potential SWM detention alternatives near Stillfried Lane and recommend an
underground detention pipe design per the sketch attached. During the call, a couple of other ideas
were floated — gravel infiltration behind curb or a grass channel / infiltration area in front of the
stone wall. We have found these options to be inadequate and problematic by creating additional
impacts. Therefore, we consider the detention pipe alternative shown in the attachment to be the
best option, because it maintains much of the original design footprint/elements within the project
area and maintains existing drainage patterns.
However, this alternative will no longer alleviate the existing drainage issues at the Stillfried / Ivy
intersection to the same extent as the previous design. In the original design, we had proposed
capturing the runoff reaching the existing grate inlet at this location and rerouting it to the [more]
adequate storm sewer on the UVA property — leading to the over -sized detention pipes. This
alternative proposes to keep the existing 10" Iron outlet pipe leaving Structure 3-8. While the total
flow to this pipe will be reduced by the alternative design, it will remain near 400% full during the
design storm. Survey was unable to confirm where this 10" pipe ultimately discharges. However, per
the approximate direction and elevation information, it is assumed that the pipe discharges to the
existing roadside ditch on the north side of Ivy Road.
Ultimately, this alternative SWM design will meet the SWM Quantity criteria, provided water does
not significantly back up into the detention pipes due to the inadequate outfall and negate the
provided storage. The existing 10" pipe has a capacity of approximately 1.67 cfs and must convey
approximately 6.6 cfs in the 10-year storm. Therefore, the alternative design is unlikely to effectually
mitigate the potential problems resulting from the existing drainage situation. However, this design
provides a significant volume increase below the roadway surface to offset an very minor increase in
runoff (approx. 0.07 cfs in the 10-year storm). Therefore, this design will not make the pre -
development condition worse.
On another note Jack, we will need to have an additional discussion on Kimley-Horn's fee to
redesign this area this late in the plan process. However, we can resolve that matter after we
establish the best way to move forward.
Please let us know your thoughts on the above recommendations once you get a chance to review
them. If you have any questions, let me know, and we can set up another call if you like.
Thank you,
Michael
Michael R. Mitchell, PE
Kimley-Horn 11700 Willow Lawn Drive, Suite 200, Richmond, VA 23230
Direct: 804 292 2070 1 Mobile: 804 512 7892