FLOOD07908

• Designation Number: 260
• County: Jefferson
• Community: Unincorporated Jefferson County
• Basin: South Platte
• Title: Major Drainageway Planning - Sanderson Gulch/Weir Gulch Volume I
• Date: 8/1/1972
• Designation Date: 12/1/1987
• Floodplain - Doc Type: Floodplain Report/Masterplan

West of Mead St. an open channel with 3:1 and l:lslopes is again
proposed.

the flood plain area and should be treated the same as
described in Drawing W-5. The Virginia St. crossing requires
the replacing of the existing culvert with a box culvert capable
of passing the 10 year storm.
The sections of channel from Virginia to Wolff, from Wolff to
Custer, and from Custer to Wolff are similar in nature. It is
recommended to utilize an open Channel with 3:l side slopes,
where possible, and steeper side slopes, up to 1:1, when
dictated by space constriction.

Drawing No. W-4

Improvements from Newton St. to First Ave. are very similar to
those for Drawing W-3. The channel is constructed to the maximum
capacity possible, recognizing existing right-of-way limitations.
Channel cross sections are similar in nature to those described
for Drawing W-3. The bridges proposed for Newton St. and Osceola
St. will pass storms up to the 100 year frequency without over-
topping. This is possible due to the elevation of the street in
relationship to the channel invert. The conduits for Perry St.,
Quitman St.,and 1st Avo. arc designed to pass the 10 year storm
without overtopping but will be inundated by the 100 year storm.
Much of the area surrounding the channel is still in the 100 year
flood plain, although property damage resulting from such an
event arc significantly less than those under historic conditions.
All construction within the 100 year flood plain should be limited
to that acceptable under the flood plain regulation ordinance.
From 1st Ave. to Bayaud AVe., the gulch flows through an area
developed by the Denver Parks Dept. and very little improvement is
necessary.

At the Wolff St. crossing a bridge is recommended.
tion of the street, the bridge will be capable of
to the 100 year storm runoff.
The Custer Place and upper Wolff St. crossings are box culverts,
capable of passing the 10 year storm flow.

Due to eleva-
passing up

Drawing No. W-S

Portions of flow from storms greater than the 10 year occurrence
will be diverted to the north along Wolff St. at the upper cul-
vert to re-enter the gulch near the lower culvert. Relatively
little property damage is expected from this channel cutoff.
From wolff St. to Sheridan Blvd. the gulch flows through an
area of existing public ownership. This area is to bc flood plain
zoncd coupled with very minor improvements consisting of one check
dam and regrading the channel invert as it approaches the Wolff St.
culVert. The Parks Department may continue their program of
grading and grassing of the channel through thi~ reach a~ their
funds permit.
Drawing No. W-7

A new box culvcrt is indicated beneath the intersection or Bayaud
^ve. and utica st. From this intersection to Alamona Avo., the
gulch flows through an area developed by the Denver Parks Depart-
ment. The only necessary improvement is in the installation of
one check dam.

^ ~a~allcli~g cc~duit i~ ~~opozed be~eath Alameda AVe. such that
tho combined capacity is sufficient to pass the 10 year storm
runoff. Gabion slope protection on both the upstream and down-
stream faces of Alameda Ave. is recommended to control the extreme-
ly steep slope and to prevent serious erosion during overtopping
of Alameda Ave.

h new conduit is proposed benea~h Shorida~ 31vc. cc~ablc of
passing the 10 year storm design runoff.

Minor channel improvements will be necessary approximately 200
feet west of Sheridan Blvd. to provide an approach section to the
culvert.

Upstream of Alameda Ave., the gulch flow>! through an open area
whiCh is still in private ownership. Although this area is flood
plain zoned, it is recommended that it be acquired by the Parks
D<=p...cUUoolll rai: <1..v..lopm",nt. Rec..-nr..,eilded cross s,",ctions and channel
invert profilcs arc shown On the master planning sheet but they are
not integral to the functioning of the entire drainage system.
If additional storage can be developed behind the Alameda Ave.
crossing, it will have a beneficial flood routing effect.

The remainder of the area between Sheridan Blvd. and Ohio Ave.
should be flood plain zoned. The Channel slope is gentle enough
that relatively little erosion should be caused by major storms
and channel improvements are not ju~tlii~u.

Drawing ~o. W-6
North of Virginia Ave., the gulch flows through a continuation of

^ box culvert is proposed for Ohio Ave. capable of passing thc
10 year storm runoff. Upstream of Ohio Ave. the channel flows
through an area extremely constricted by residential development.
The channel cross section varies from a 3:1 side slope, grass-
lined chann~l to a 3,1 and j,lside sloped Channel with gabion
slope protection On the l,l side, to areas with vertical con-
crete retaining walls. Right-of-way must be purchased ~or this

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