HomeMy WebLinkAboutChris Smith Drainage Study Comments 082422From: Smith, Christopher J.
Sent: Wednesday, August 24, 2022 11:15 AM
To: Thrower, Torrence <tthrower@littlerock.gov>
Subject: RE: For Z-9716
My comments on the “drainage study” are below:
Provide a sheet showing the pre and post construction drainage areas used to calculate the design storms runoff from each subbasin equal to the total site discharge.
Provide rational method calculations for each subbasin pre and post construction for each design storm event (25-year, 100-year, etc.).
Detention ponds routing calculations for each design storm event including the 25 & 100-year storms.
The storm sewer system is required to collect and convey the 25-year storm to the detention ponds. The detention ponds are required to have enough volume to detain for the 25-year storm
per City Code. Collecting, conveying, and detaining for the 100-year storm is recommended but not required. Hydraulic calculations for each design storm event for the storm sewer system
will be required to be submitted as part of the final drainage study to the Department for the future grading and building permits for the project if approved by the Planning Commission
and Board of Directors.
Show storm sewer system and detention pond outlet structures on preliminary plat. Detention pond outlet structure profile and cross-sectional views shall also be shown on the preliminary
plat including the 100-year emergency spillway.
Show drainage flow arrows with slopes on how stormwater runoff drains to the site, drains on site, and drains off site pre and post construction.
Regards,
Christopher Smith, P.E.
Design Review Engineer
City of Little Rock
Planning and Development ─ Engineering
723 West Markham Street
Little Rock, AR 72201
Office: (501) 371-4817
Cell: (501) 414-1848
Fax: (501) 399-3435
https://www.littlerock.gov/