FLOOD02174

• County: Denver
• Community: Lakewood
• Stream Name: Dry Gulch
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 7/1/1979
• Prepared For: Denver
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

Description of Proposed Improvements: Sheet l4

The channel in this reach is contained within steep banks in a

deep channel with no significant flood hazard. The existing box

culvert under Perry Street is not adequate to convey the lO-

year flood; a relatively small degree of overtopping would occur.

The street would be significantly inundated in a lOO-year flood.

In neither case would flooding of homes be expected. As a result,

improvements to the Perry Street crossing are deemed unnecessary.

Estimated Cost of Proposed Improvements: Sheet 14 (Reach A)

Item Description Quantity Unit Unit pr.ice Cost
CONSTRUCTION
Excavation for Open Channel 22,500 C.Y. $ 3 $ 67,500
Concrete Low Flow Channel 380 C.Y. 210 79,800
Slope Protection 3,050 C.Y. 22 67,100
Slope Protection Filter 800 C.Y. 17 13,600
Maintenance Roadway 3,000 L.F. 14 42,000
Drop Structures 8 Ea. 5,000 40,000
Rip Rap Protection at Perry Street 1 L.S. 12 , 000 12,000
Construction Sub-total $322,000
15% Engineering 48,300
10% Contingencies 32,200
Total Construction $402,5PO
LAND ACQUISITION
Right-of-way Acquisition 4.1 A 15,000 61,500
10% Contingencies 6,150
5% Legal 3,075
Total Land Acquisition $ 70,725
TOTAL COST $473,225

In the Phase A report (Reference 2 ) a question was raised

regarding the ability of the Perry Street embankment to withstand

the hydrostatic forces created by the upstream ponding of flood-

waters. Subsequent evaluation of the embankment indicates that

the stability is adequate. No structural failure would occur

unless severe erosion took place on the downstream face of the

roadway. Rip-rap protection of this slope is recommended, as

shown.

It is recommended that Dry Gulch be improved by the construction

of er0sion control structures, a low flow channel, reshaped side-

slopes to be 4:l with grass where possible, and 2:l with lining

where shown. A maintenance access roadway is recommended, and

considerable right-of-way is required. These improvements can be

deemed to be of low priority, since there is no flood hazard and

since the channel is not presently exhibiting erosion damage.

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