FLOOD04421

• County: Arapahoe
• County: Douglas
• Community: Arapahoe, Douglas
• Stream Name: Piney Creek, Cottonwood Creek, Lone Tree,
• Basin: South Platte
• Title: Flood Hazard Area Delineation
• Date: 10/1/1975
• Prepared For: UDFCD
• Prepared By: Arapahoe, Douglas
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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13

Throughout the Lone Tree Creek study reach, the flood plain is well

defined. Flood plain widths vary from 500 to 600 feet in the

lower reaches below Arapahoe Road to less than 50 feet above the

runway backwater.

Above Mississippi Avenue to Jewell Avenue, the flood plain

narrows into a well defined channel area. No structures are en-

dangered through this reach. At Jewell Avenue, the road will be

overtopped during the 100-year event.

Murphy Creek - The flood plain limits and water surface profiles

for Murphy Creek are shown on the Flood Hazard Area Delineation

Drawings MC-l through MC-IB.

Murphy Creek joins Sand Creek west of Piccadilly Road in Arapahoe

County. Piccadilly Road crosses Murphy Creek at grade without a

culvert or bridge. As a result, the road is flooded quite fre-

quently. The 100-year flood plain limit for Murphy Creek com-

bines with the Sand Creek flood plain north of Alameda Avenue.

The area of inundation by the combined flood plains is shown

on Drawings MC-l, MC-IA" MC-IB and MC-2. The farm buildings

located west of Picadilly Road near the confluence of Sand Creek

and Murphy Creek could be susceptible to flood damage from flood

events less frequent than the 100-year event.

At Station 196+00, Drawing MC-7, a farm structure is susceptible

to undermining and resulting damages during periods of high flood

flow. No other improved facilities are located near the flood

plain between Jewell Avenue and Airline Road except for two dump

roads. These roads would be overtopped during periods of high

flood flow.

The culvert structure at Airline Road is adequate for the 100-

year flood flow. Upstream of Airline Road, the flood plain is

contained within the existing, well-defined channel and presently

provides no threat to adjoining properties.

Flood Plain and Floodway Data

Above Alameda Avenue, the flood plain is contained within a wide

valley section. No structures exist near the flood plain except

the pipe and bridge structures at Alameda and Mississippi. Both

road systems will be overtopped during a 100-year flood event.

This reach of Murphy Creek is planned for future land uses

ranging from open space to residential and light industrial.

The limits of future flooding are outlined on the attached draw-

ings and tabulated in Tables 6, 7, 8 and 9, Flood Plain and Flood-

way Reference Data. The tables list the potential flood elevations,

flooding widths and channel bottom elevation at each cross section

for the four streams studied. The flood profile, channel bottom

profile and flood plain width at any point on the streams is