FLOOD04954

• County: Costilla
• Community: San Luis
• Basin: Rio Grande
• Title: Subsurface Drainage Feasibilty Study
• Date: 9/1/1996
• Prepared For: Costilla County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The preliminary design for the subdrain system is presented on plates 1 through 3. The
plan consists of the following features:

. An outfall structure and flap gate at station 0+00

. 70 feet of solid 12" PVC from station 0+00 to station 0+70

. 345 feet of solid 12" PVC from station 0+70 to station 4+ 15

. 460 feet of perforated 10" PVC with sock from station 4+ 15 to station 8+75

. 180 feet of perforated 10" PVC with sock from station 8+75 to station 10+55

. 230 feet of perforated 10" PVC with sock from station 10+55 to station 12+85

. 560 feet of perforated 10" PVC with sock from station 12+85 to station 18+45

. Four lateral lines (2,460 feet total length) of perforated 10" PVC with sock

. Six standard 48" manholes at stations 0+70, 4+15,8+75, 10+55, 12+85, and 18+45

. Four cleanouts, located at the upstream end of each lateral line

The cost estimate for the recommended subdrain system is presented in table 2.

Installation of a subdrain system in the southern portion of town, south of Gaspar Street,
would be unfeasible due to engineering constraints, geologic features, and lack of ground
slope. Additional recommendations are described briefly below.

Montez Ditch Rehabilitation
The Montez Ditch should be properly maintained or abandoned altogether. The lower
portion of the ditch within the town should mled in to the proper grade if the ditch is to
be used for irrigation purposes, or completely filled in if it is to be abandoned.

Caooin!1: of artesian wells
Existing artesian wells located within the city should be properlJ capped. The use of
artesian wells is not completely discouraged, however the wells should not be allowed to
flow freely during times of non-consumptive use.

Extension of the "Ve!1:a Ditch"
The existing "Vega Ditch" that runs parallel to Vega Street could be extended to Culebra
Creek. This extension would require a siphon or other structure to cross the People's
Ditch and would require and easement through private property. The benefits resulting

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