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Categorical Exclusion Determination:
For the City of Sheridan, Wyoming
Sheridan WWTP South Clarifier Component Replacement Project
Sheridan County, Wyoming
The Wyoming Department of Environmental Quality/Water Quality Division (WDEQ) has conducted a review of the proposed Sheridan WWTP South Clarifier Component Replacement Project in accordance with EPA and State of Wyoming procedures for implementing the State Environmental Review Process. DEQ has determined that this project is eligible for a categorical exclusion. Accordingly, DEQ is exempting the project from further substantive environmental review requirements under the State Environmental Review Process. Neither an Environmental Assessment/Finding of No Significant Impact nor an Environmental Impact Statement/Record of Decision will be required for the proposed action. The following is a description of the situation and the proposed action and a statement of how the action meets the criteria for a categorical exclusion.
The Sheridan Wastewater Treatment Plant is in need of several upgrades and improvements to address immediate health and safety needs, continuation of community wastewater treatment service, and environmental protection needs. These projects have been prioritized and the goal is to replace, improve, and modify crucial unit processes reaching obsolescence and presenting significant risks, not only to the health and safety of Operations staff and community, but also of the capability of the facility to ensure uninterrupted processing of the City’s wastewater to achieve and/or maintain an adequate minimal level of service. The recommended priority improvements listed below are the most pressing and highest risk assets among those identified at the treatment facility. Each of the priority projects are introduced in the following phases.
The first phase of the project consists of removing the existing 40+ year old clarifier center support column and sludge scraper mechanism and replacing the mechanism with a new center support column, scraper mechanism, motor drive, gear box, and any pertinences that pertain to the upgrade. The current sludge scraper mechanism in the south clarifier has recently experienced operational problems and this clarifier is currently not available for use. The facility only has two clarifiers, with only one currently operational. Under the current conditions, if the existing north clarifier were to have any interruption of service, the facility would not be able to adequately treat the wastewater.
The other phases of the overall project will include site electrical improvements, including replacing the primary electrical service from Fort Road into the facility, installing a new transformer, and installing a new switch gear to replace the existing obsolete equipment. Heating and ventilation improvements, including replacement of exhaust fans, intake louvers, air handling and heating equipment among various buildings to ensure adequate ventilation is available to maintain non-hazardous conditions. Raw sewage pump station (RSPS) drywell upgrades, including new pumps, valves and piping, electrical motor control panels, and variable speed drives. Only the existing RSPS wet well would remain part of the pump station upon completion. The proposed solution would significantly improve the operator safety provisions and provide a system with readily exchangeable parts, thereby, resolving the reliability concerns present with the existing system. Installation of a second, identical dewatering belt filter press, to both add capacity and provide redundancy to this critical part of the treatment process. It also includes the upgrade of the undersized sludge feed pumps to both meet capacity of the existing press and accommodate the added sludge dewatering capacity.
To fund this project, the City intends to use funds from the Wyoming Clean Water State Revolving Fund (CWSRF) loan. The City will present the preliminary design of the proposed project at the public meeting to be held on May 25, 2023. The total cost of the project is estimated at $1,200,000. Of this total project cost, the City plans to obtain the loans with a 1.25% interest rate, if principal forgiveness is not available. The Sewer Fund Rate Revenues will repay the loan.
The City of Sheridan is aware of and accepts the fact that they will be responsible for any required mitigative actions associated with and including stormwater runoff, erosion control, archeological/historic artifacts, and air quality concerns. These will be part of the standard State Revolving Funds Program contract conditions.
DEQ is granting an exclusion because the project replaces or rehabilitates existing infrastructure within the Wastewater Treatment Plant property boundary and in an area that has been previously disturbed. DEQ has determined that exempting the proposed project from further review under the State Environmental Review Process will not result in adverse impacts to the population or the area of the City of Sheridan or Sheridan County, Wyoming.
The documentation to support this decision will be on file in the DEQ Cheyenne Office and is available for public scrutiny upon request. Comments concerning this decision may be addressed to Shawn King, SRF Project Manager, Department of Environmental Quality, 200 W. 17th St. Suite 200, Cheyenne, WY 82002. Tel. (307) 777-6941, FAX (307) 635-1784, email: shawn.king2@wyo.gov.
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