FLOOD00031

• Designation Number: 38
• County: Jefferson
• Community: Lakewood
• Title: Major Drainageway Planning - Sanderson Gulch, North Sanderson Gulch, and Weir Gulch Volume I
• Date: 8/1/1972
• Designation Date: 12/1/1974
• Floodplain - Doc Type: Floodplain Report/Masterplan

oocurrence,;. The majority of exi,;tiny cro~>;iny>; have be",n left in
place, although their capacity may be as small as the 5 year
runoff. In specific areas where economic analysis indicated
that the benefits derived from a ncw street crossing would be
greater than the cost of that crossing, new facilities have
been recommended.

area. The approach taken in the In,,,,,ter p!drl i8 tu inHtdll iln
additional conduit from Jewell to Wadsworth consistent with
existing development and uti1ity oonstraints and then determine
the frequency storm which can be passed by the structures.

SANDERSON GULCH THROUGH LAKEWOOD

From the Jewell crossing to the Jewell Park area, the standard
design criteria of 10 year frequency conduits together with a
channel capable of transmitting a 100 year storm has been possi-
ble. Again in this area, Lakewood is concerned that Jewell
Avenue remain open during a 100 year storm evcnt. Particular
care must then be taken with street crossings to assure that the
100 year storm does not infringe upon Jewell Avenue excessively.

The first area encountered in Lakewood on Sanderson GUlch is
the Bit- O-Sea Development which is clustered around 2 recreational
reservoirs. Based upon the legal aspects of these reservoirs, and
the desire of the residents that they remain in their existing
condition, the design criteria for this area is to assure the
safety of the reservoirs with a minimum of disturbance to the
area.

Criteria for the Jewell Pond involved improving it to function
as an effective detention reservoir while fitting with the park
development.

Directly above Bit- O-Sea Reservoir area is the Clair field
Reservoir. This reservoir is still in an undeveloped area and
repre"ents an excellent opportunity to develop a necessary flood
detention facility. The criteria here is to maintain the 100
year flood pool with improvements as near as possible to the
historic 100 year flood pool area, The reservoir must also be
improved to a state that is acceptable to the State Engineer
in a developed area, while having a maximum effect as a flood control
reservoir.

Within the Jewell Park area is the crossing of Agricultural
Ditch across Sanderson Gulch. In compliance with the recommenda-
tions of the legal counsel, together with good engineering prac-
tice, a suggested method of separating flows in this area was
designed. The criteria for this grade separation is that run-
off from storms up to the 100 year frequency in the main gulch
Should not enter the irrigation ditch.

The next area with specidl design considerations on Sanderson
Gulch is the Green Gables Country ClUb Entrance Road Area. The
area above this entrance road is subject to inundation on a very
frequent basis due to the very small culverts under the road.
It wa~ originally hoped that this road could be left in its
existina condition to act as u flood detention reservoir with.
the only improvements being placing of slope protection on the
downstream side of the road. Additional surveying indicated
major errors in the available mapping such that the frequency
of the inundation for the road became too often for acceptable
standards.

The next area where specific design criteria was employed occurred
at Smith Reservoir where the criteria was to develop a method
to maintain spillway discharges from Smith Reservoir in the
Sanderson Gulch Basin.

NORTH SANDERSON GULCH

The fin,,-l eesign criteria adopted for the Green Gables site
involved the design of larger conduits beneath the road fill and
raising the road fill to a point where the reservoir routing
effect made the conouits capahlp of passing a 100 year storm
beneath the road. This approach will significantly reduce the
frequoncy of inundation to the golf course area and overtopping
of the road.

The specific design criteria on North Sanderson Gulch from
Pierce Street to Florida Avenue was essentially the Sdffie. A
channel was developed with a maximum capacity reasonable within
the available right-of-way and remaining flows were allowed to
continue along the street system. This approach generally means
that crossings are designed for a 10 year frequency with the
channel capacity being somewhere between a 10 year and 100 year
capacity. One exception to this is the Wadsworth crossing Which
is capable of conveying the 100 year storm runoff across Wadsworth
Blvd. as requested by the City of Lakewood.
The conduit in Florida Blvd. is intended to carry local drainaqe
from the surrounding area and base releases from the Green Gablc's
Park detention pond. Additional flows arc to be carried on the
street surface with reasonable limits of inundation.

Oesign criteria for the area from Wadswcrth Blvd. to Jewell Ave~uc
was influenced by the city of Lakewood's request to inc~ease the
cupucities beneath Jewell and wadsworth to values approaching
the Ino year occurrence. Meeting the req~ircrncnt of passing a
100 year storm beneath the mentioned streets would have been
particularly expensive in this location, since a conduit would
have been necessary across the Jewell-Wadsworth Shopping Center

The Green Gables Park improvements criteria as agreed to with the
Park and Recreation District involves leaving the pond in as

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