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WSP11822
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Last modified
1/26/2010 3:18:59 PM
Creation date
10/12/2006 5:11:50 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8240.200.43.J
Description
Grand Valley/Orchard Mesa -
State
CO
Basin
Colorado Mainstem
Water Division
5
Date
9/19/2000
Title
Draft Environmental Assessment - Orchard Mesa Wildlife Area Selenium Remediation Project
Water Supply Pro - Doc Type
Publication
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<br />Orchard Mesa Selenium Remediation Environment Assessment <br /> <br />4 <br /> <br />. a long-term fix <br />. cost effectiveness <br />. public acceptance <br />. easy to maintain with low operation & maintenance costs <br />. consistent with wildlife area purposes & objectives; not cause any degradation to <br />wildlife area functions <br />. adaptable to anticipated long-term Colorado River course changes <br /> <br />From this screening, alternatives were developed for further study and refinement. Following <br />further consultations with geomorphology and endangered fish experts, the following final array <br />of alternatives were developed. <br /> <br />Alternative 1. No Action - The No Action alternative would take no action to address high <br />selenium concentrations in the backwater areas and selenium bio-accumulation would continue <br />at the OMW A. Associated affects to fish and aquatic birds would also continue. <br /> <br />Alternative 2. Pipe and Dilute - Selenium contaminated return flows from two surface drains <br />would be diverted away from the East backwater directly into the Colorado River through buried <br />pipelines. The water discharged directly into the river would mix and be diluted by the much <br />larger river volume. A flushing channel would be cut to route clean river water to dilute <br />selenium concentrations in the West backwater. Mitigation for lost habitat would involve new <br />habitat improvements within the OMW A or at another location along the Colorado River. The <br />estimated construction cost of the Preferred Alternative would be approximately $83,000 and <br />annual expenditures for operation and maintenance would be about $6,000. <br /> <br />. This alternative was the ID and agencies' Preferred Alternative. On-site meetings with <br />representatives of the Recovery Program, Corps of Engineers, Service, Mesa Land Trust <br />(operators of the wildlife area) and Reclamation were held on July 12 and August 17,2000 to <br />discuss exact locations of the improvements and other "specifics" of the plan. <br /> <br />Alternative 3. Construct New Wetlands and Dilute - A new wetland area would be excavated <br />near the East backwater area which would be designed to fill with "clean" water infiltrating from <br />the Colorado River. This area would then serve as replacement habitat when beavers and their <br />dams in the East backwater are removed to prevent ponding of irrigation drainage (and the <br />resulting selenium bio-accumulation). The contaminated drainage would be routed directly to the <br />Colorado River where it would be mixed and diluted in the much larger river volume. Also, a <br />channel to route clean river water would be cut to dilute selenium concentrations in the West <br />backwater. The estimated construction cost would be approximately $83,000 and annual <br />expenditures for operation and maintenance would be about $6,000. <br /> <br />Alternative 4. Replace Habitat Off site - clean habitat (currently inaccessible to endangered fish) <br />would be acquired at another location along the Colorado River to replace the contaminated habitat <br />at the OMW A. This property would be developed for use by endangered fish and other wildlife. <br />
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