Simi Valley, California
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The City of Simi Valley
The Big Sky/Sand Canyon residential development in Simi Valley, Califfornia, design was complicated due to the number of stakeholders and site constraints.
Design began in March 2003 and involved identifying the design inputs and sizing the systems. The final plan included 12 separate storm drains with diameters ranging from 24 -in. (610 mm) to 66 -in. (1676 mm). The storm drains served drainage areas ranging in size from eight to 160 acres (3.2 to 65 hectares).
Detailed hydraulic grade line analysis was required
to meet the requirements of the specifying engineer and was based on the 100-yr recurrence
interval. Conveyance flows ranged from 33 to 532 cubic feet per second (0.93 to 15 cubic meters
per second). Treatment flows corresponding to 10 percent of the 50-yr runoff event ranged from
2.75 to 44.3 cubic feet per second (0.077 to 1.25 cubic meters per second). To be cost competitive,
it was necessary to bypass flows greater than the treatment flow around the Vortechs Systems
using 12 Vortechs Bypass Structures (VBPs). A total of 12 Vortechs Systems were sized to reduce
total suspended solids by approximately 80% based on particle size typical of the site. In addition
to removing sediment from runoff, floatable debris, oils and grease are also being treated. The total
sediment storage volume for the project is 93 cubic yards (71 m3).
One of the 12 Vortechs Systems is the largest system ever to be installed in California and also a
first-of-its-kind for Contech Construction Products Inc. The original plan specified a cast-in-place
(CIP) system with an inside width of 22 -ft. (6.7 meters) and inside length of 33 -ft. (10.1 meters) but
because of construction cost and schedule limitations, the Contech’s team of structural engineers
and precasters designed a tilt-up, panelized wall system. The panelized wall system cut the
installation time from weeks down to a few days.
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