HomeMy WebLinkAboutCorrespondence Miscellaneous 7/28/2008
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EGR & Associates, Inc.
Engineers, Geologists and Surveyors
25358 Prairie Road
Eugene, Oregon 97402
(541) 688-8322
Fax (541) 688-8087 ,
July 23, 2008
Don Haase.
1960 Gilham Road
Eugene, OR 97401
RE: Skycheif Stonnwater Construction Phasing
Dear:~.Haase
Per your request we have contacted the City of Springfield regarding questions about development of the
stonnwater system & grassy swale treatment area:--Andy Lindberg with thc city requested that an engineer
prepare a letter documenting procedures to ensure proper operation of the stonnwater treatment and detention
area during construction of the site improvements and duplex homes.
It is our understanding that this project will follow a nonnal construction schedule and that there are no long
tenn delays or phasing expected. The expected schedule will begin with rough grading, then installation of the
underground utilities. Home construction would typically follow with the fme grading, paving, and landscaping
coming at the end of the project.
The stonnwater treatment and detention swales will be rough graded at the first stage of the project. The catch
basins, stonnwater piping and outlet control orifice would be installed at the same time as the utilities. At this
point the stonnwater collection system and detention area will be fully functioning. Until the time when the
swales receive top soil and seeding, the swale will need to be monitored for signs of erosion from the site.
Measures that can be taken by the contractor as needed to ensure sediment laden water does not leave the site
include; placing plastic, mulch, or straw over exposed soils (including the swale), placing sediment barriers at
the discharge point, or excavating settling basins. There are many other tools that the contractor can employ to
control erosion. The extent of the erosion control measures required is dependent on the season of construction
and site conditions. EGR &Associates will be available to provide guidance during construction as needed.
Depending on the weather and unforeseen temporary changes in the site runoff patterns the contractor may need
to construct temporary dikes or ditches to route runoff to the stonnwater system from areas such as behind stock
piles or excavated foundation areas. Should there be any long tenn delays we recommend that you apply
temporary seeding to all exposed areas.
Please note that discharge of Slormwater onto this site from adjacent properties was not expected from the
original survey and no additional provisions have been made for off site water.
If there are any questions concerning operation of the stormwater system during construction please feel free to
give us a call.
Sincerely,
EGR & Associates, Inc.
Dan Olmstead, PE
Civil Engineer
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Date Received:
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CC: Andy Lindberg, City of Springfield