FLOOD05115

• County: Boulder
• County: Weld
• Community: Erie
• Stream Name: Coal Creek
• Basin: South Platte
• Title: Floodplain Information Report
• Date: 8/1/1980
• Prepared For: Erie / Boulder County / Weld County
• Prepared By: Water Resource Consultants
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

TABLE-I, CONTINUED

the information in Table-4. The U(,odedareas for Coal Creek are presented
on Plates I through 4.

Field
Identification

Elevation

SCS-BM_2

49B5.37

Location

The 100-year floodplain, aa delineated on the flooded atea maps, meets
the requirements of the State Floodplain Management Program. Upon officIal
approval and designation of this report by the Colorado Water Conservation
Board, these water aurfaee elevations and flooded areaS for the 100-year
flood will aupersode all previous flood ha~ard information and data for
the administration of the subject floodplains.

SCS-BM-3

5010.71

SCS-BM-4

5024.95

USC&GS

5024.96

SGS-BM-5

5057.77

Cap and Rebar, N. side of Kenosha Rd.
47; N.W. of intersection of County
line Rd. and Kenoaha Rd.; 7' s. of
Cone. hr. strlL.; 2' W. of Tel. pole.

Cap and Rebar, 2' s. of fence post;
14' north of N. rail over irr. canal;
26' N. of centerline of gravel road.

Cap and rebar, 2' S. of street sign
(PierceandPerryStreet);13'S.II,of
red fire hyd, 37' N.II. of intersection
of Pierce and Petty St.; 176' N. oI
N. railroad track.

D. Floodway Delineation

When encroachments onto the natural floodplain are allowed, such as
artificial fill, the flood carrying capacity is reduced, The depth of water
or the flow velocity in the remaining floodplain ate a ~U8t normally increase
to convey the Same magnitude of flood, and thus the flood hazard to areas
near the encroach~nt may be increased. However, the economic gain from
developments or encroachments onto the floodplain must be weighed against
the resulting increased flood hazard. Floodplain management programs gUst
determine the acceptable limits of encroach~nt which will allow opti~um
econc~ic uSe of the floodplain.

At Erie, nesr S.E. 'corner of city
limits; 0.2 mi. E. of Kuner Pickle
Plant; 44 ft. ~. and 1 ft. lower
than Colorado State Highway 240: 37 ft.
E. and I fc. lower than center of
Crsck; in concrete post; sCandard
tabletstamped"JR-5J-19485026."

Cap and rehar, l' N.W. oI Cone. fence
corner post. E.II.-N.X. fence line.
Appr"",5ClO'S."foldco.l..inepil;
lO'E.ofcentctlineofN.-S.lane.

C. Flooded Areas

i
I

The concept of the floodway haa been adopted by the National Flood
Insurance Program as a tool in assiating local communities in this aspect of
floodplain management. The floodway ia defined as the channel and floodplain
width which must be kept free of encroachment such that the IOO-year flood is
conveyed "ithout "substantial" increases in flood depths, As a ..inimu.., standard,
FEtiA li~its the depth increase to 1.0 loot provided hazsrdous velocities are
not produced. The following table lista the Iloodwsy criceria recommended
by the agencies sponsoring this study in their respective jurisdictions.

The Ilooded ares maps are derived from the water surface profiles,
The hase ~apping published in this report has a 2-foot contour interval
and a acale of I-inch equal to 400 feet, If needed. the floodplain prod"~ed
by other frequency Iloods could he readily delineated on these maps using

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