HomeMy WebLinkAboutINDIAN HILLS VILLAGE FINAL PUD - 81 93A - CORRESPONDENCE - CITIZEN COMMUNICATION4. Additional questions about the calculations of the size of
the drainage ditch, provided by Lugunitas, is that the width
of the ditch channel is shown to decrease from 16 ft at the
upper end (Station 5+00) to about 12 ft at Station 3+50. If
the width is narrowed then flow velocity also has to
increase for the same or a greater amount of water flow
through the narrowest parts of the drainage ditch.
Actually, a larger _volume -of -water .-.must_. be -calculated since
the additional drainage area has added about 2.4 cfs of
water into the channel between Stations 5+00 and 3+50.
5. It appears that the side of one of the houses is serving as
part of the drainage channel at point 3+50?
6. Considering the vertical elevation drop, considerable water
velocity should be planned for as the drainage channel
approaches Stuart St. However, the ditch is shown turning
nearly a right angle next to Stuart. If sufficient velocity
results, then the momentum of the water would carry it out
of its channel, and possibly onto Stuart at that point.
7 Finally, considering the total size of the project and the
amount of water that must be drained, are two 24 inch
culverts, placed under Stuart, large enough?
Sincerely yours,
cc: Jonathan Prouty
May 16, 1994
Commun. Ping. & Envrmmntl Srvs.
P.O. Box 580
235 Mathews Street _
Fort Collins, CO 80522 -- - - - -- - - - - - -- - - _ _
Dear Sirs,
The purpose of this letter is to express concern that off -site
impacts of drainage water from the proposed Indian Hills Village
PUD (IHV-PUD) along Busch Ct. (Drainage Basin' E) have still not
been properly considered for the following reasons: --
1. Currently, the Busch Ct. Neighborhood Group has been unable
to ascertain whether there is any agreement with Indian .
Hills West that the drainage discharge that they contribute
to the IHV-PUD will not increase. Currently, the proposed
designs show that, for a 100 yr storm, Indian Hills West
would contribute 23.9 of the total 28.2 cubic feet second
(cfs) of surface drainage water that must discharged through
Basin E to eventually cross Stuart Street and flow into
Spring Creek. A written and legally binding agreement that
this discharge will not be increased appears necessary to
assure that the planned drainage capacity along the boundary
of IHV-PUD and the Busch Ct. Neighbors is not exceeded.
2. The land -surface elevation of South side of Indian Hills
West (along the Arthor Ditch) is 4990 ft.. Water is then
discharged off of Indian Hills West onto Basin E of the
IHV-PUD from a land -surface elevation of about 4980 ft and
discharges at Stuart Street at an elevation of about 4966
ft. The vertical drop from the Arthor Ditch to Stuart
Street is about 24 feet over a total distance of about 970
ft. The vertical drop from the top of Basin E to Stuart
Street is about 14 ft over a distance of about 570 ft.
3. The calculations provided to us by the Lagunitas Company of
the size of the ditch required to accomodate storm drainage
along their west boundary need to be questioned because they
show the flow velocity of the water decreasing with distance,
along the drainage ditch, even. through the land elevation
has dropped dramatically (see Item 2 above). This just
isn't possible, since the effect of gravity on the water
velocity must be considered.