HomeMy WebLinkAboutWARREN FEDERAL CREDIT UNION - PDP - PDP150011 - REPORTS - DRAINAGE REPORTMr. Wes Lamarque
November 17, 2015
Page 2 of 5
Lots 1, 2 and 3 and Tract A correlate with basins 103a and 103b of the Northwest Roads
Ultimate Drainage Plan. Please refer to the attachments for Sheet 10 and 11 of the Northwest
Roads Ultimate Drainage Plan.
PROPOSED DEVELOPMENT
The drainage for this site has been designed to be less than the maximum allowable runoff from
each basin as stated in the Overall Rigden Farm drainage plan. Table 1 compares the actual
runoff versus the allowable runoff from the Northwest Roads Ultimate Drainage Plan. Runoff
from the four basins (A, B1, B2 and C) are to follow the intent of that plan and are to be
collected in storm inlets and piped to the North Tributary Storm Sewer in Drake Road. Please
refer to the attachments for the hydrologic calculations of the 10 and 100 year storm events that
were performed utilizing the Rational Method.
Table 1. Comparison of Flows.
Rigden Farms Northwest Roads Warren Federal Credit Union Subdivision
Basin ID
Contributing
Area
(Acres)
100-yr
Design
Runoff
(cfs)
Basin ID
Contributing
Area
(Acres)
100-yr
Design
Runoff
(cfs)
103b 0.93 9.3 A 0.52 5.1
103a 1.15 11.4 B1 0.44 3.8
B2 0.79 7.2
C 0.26 2.3
Totals 2.08 20.7 2.01 18.4
103b 0.93 9.3 A 0.52 5.1
103a 1.15 11.4 B1, B2, C 1.49 13.3
BASIN DESCRIPTIONS
The site is divided into four basins: A, B1, B2 and C.
Basin A is 0.52 acres and is comprised of drainage from the roof of Lot 3 and on-site sidewalks
and landscape areas. Water will flow from the roof drains into the proposed drainage system that
ties into an existing stub from the existing storm system in Limon Drive. Water from the
proposed sidewalk along Limon Drive will sheet flow into the curb and gutter of Limon Drive
where it will then be collected by the existing inlet in Limon Drive.
Basin B1 is 0.44 acres and is comprised of the eastern portion of the Tract A parking lot, on-site
sidewalks and landscape areas. Water will flow into the proposed parking lot, across pervious
pavers and into the proposed Type C sump inlet at design point B1. From the inlet, water will be