FLOOD09085

• Designation Number: 97
• County: Adams
• Community: Thornton
• Stream Name: Grange Hall Creek
• Basin: South Platte
• Title: Major Drainageway Planning - Grange Hall Creek, Phase B, Thornton, Adams County
• Date: 12/1/1977
• Designation Date: 1/19/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

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C. Improvement Costs
A detailed cost estimate of the improvements for the selected plans was prepared

D. Plan Implementation

The improvements indicated on the master plan drawings ill each reach of the study

for the master plan drawings. The costs were divided into the following categories:

area are independent of improvements in the other reaches and, therefore, the

channel improvement, street crossing improvements, right-of-way acquisition, utility

relocation, contingency, operations and maintenance, and fiscal and administrative costs.

improvements can be constructed in any reasonable sequence. The need exists for all of

the proposed improvements; howe~er, the need for some is greater than others.

The improvement costs were then used to update the benefit/cost analysis of the Phase A
study. A summary of the benefit/cost analysis is presented in the following table:

The following table presents the recommended priority for order of implementation

according to the various reaches used in the study.

NET BENEFITS

BENEFIT/COST ANALYSIS SUMMARY
(6 3/8% Interest Rate)
(Thousands of Dollars)
COST PRESENT WORTH
Northqlenn Thornton Adams Northqlenn Thornton Refer to:
1036.2 583.4 7.34 976.1 549.6 Table IV-3,1f
114.0 64.1 .8 107.4 60.5 Table IV-3,li
19.4 26.8 0 18.3 25.2
46.8 27.0 .3 44.1 25.4
47.04 12.55 0.6 686.4 183.1 Table IV-3,1f
(Annual con-
verted to
present worth)
9.0 1832.3 843.8
1046.0 1189.0 1193.0
974.0 333.0 113.0
-965.0 -1499.3 -730.8

Priority Jurisdiction
I. Northglenn
2. Thornton
3. Thorn ton
4. Northglenn
5. Northglenn
6. Northglenn
7. Northglenn
8. Thornton

PRIORITY OF SELECTeD IMPROVEMENT IMPLEMENTATION
GRANGE HALL CREEK AND TRIBUTARIES

Item Adams
Construction I 7.7
Eng. and.zConst. .8
Services
Site Acquis. 0
Fiscal ~nd .3
Admin.
O&M .04
(Annual)

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TOTAL
DAMAGES
BENEFITS5

9.

Northglenn

I . Includes 15% contingency.
2. 11% of total of construction.
3. 4% of total of construction, engineering, and site acquisition.
4. Does not include any public costs for improvements in Reach IG.
5. Includes intangible benefits.

T otal*
Improvements Estimated Cost

Reach 4S -- Storm Sewer Improvements $167,700

Reach INE - - Street Crossings and
Channel Improvements

Reach 2G -- Street Crossings alld
Channel Improvements

182,500

213,200

Reach 9G -- Street Crossings and
Channel Improvements

34,400

Reach 8G -- Street Crossings and
Channel Improvements

176,500

Reach 7G -- Street Crossings and
Channel Improvements

317,100

Reach 5S -- Street Crossings and
Channel Improvements

Reach I SE -- Street Crossings and
Improvements to Brewer Reservoir
and Dam

51,700

104,900

Reach 2NE -- Street Crossings and
Channel Improvements

94,100

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