HomeMy WebLinkAboutGROVE AT FORT COLLINS - Filed GC-GENERAL CORRESPONDENCE - 2014-06-27Applegate
Group, Inc.
Water Resource Advisors for the West ,
July 9, 2013
Mr. Andy Reese
Project Engineer
Northern Engineering
200 S. College Avenue
Fort Collins, CO 80524
RE: Underdrain Extensions
Dear Mr. Reese:
It is our opinion that the underdrain extensions recently proposed for seep areas at The Grove
development will not, by themselves, add additional flow that will exceed the capacity of the
existing underdrain system. A qualitative visual inspection of the underdrain outfall (video taken
on June 17, 2013) shows that the underdrain system is collecting more groundwater than had
been estimated by available pre -development field data and based on a priori assumptions about
the lining and realignment of the irrigation ditch. However, the underdrain piping was designed
with excess flow capacity and it is not currently flowing at full capacity. Based on a qualitative
visual inspection of the seep areas, it is our opinion that collecting the observed seep flow in the
underdrain extensions will not exceed the remaining capacity of the system.
This opinion is limited to the seepage flows documented visually on June 17, 2013 and checked
again, visually, on July 3, 2013. This opinion is also contingent on the irrigation ditch lining
being maintained in good condition. As is always the case with the subsurface, the spatial
resolution of information about subsurface conditions is inherently limited and therefore
inherently uncertain. All contingencies cannot be anticipated and small-scale irregularities, such
as the current seep area, can never be ruled out. These limitations and uncertainties must always
be kept in mind for design and for conditions encountered during construction.
Please contact me at your convenience if you have questions or need further information.
Cordially,
Applegate Group, ine.
Tom Hatton, P.G.
Senior Project Manager
TH/ta
N:\10132 Grove at Ft Collins\Correspondence\General\Underdrain Extensions letter.docx
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