Point Woronzof Environmental Study For Effluent Beach Tower

Students: Anna McKay, Donovan Parker, Jenna Sparrowgrove,

Evan Tyler, Tom Winkler, Stephen Nuss. 

Faculty Advisor or Community Project Lead:

Osama A. Abaza, Ph.D., Professor of Civil Engineering, UAA

Stephane Nuss, Engineering Division Director, AWWU

Thomas Winkler, P.E., AWWU

James Amundsen, P.E., Chief of Highway Design, ADOT&PF

Client Organization: Anchorage Water and Wastewater Utility (AWWU)

Summary:

The Effluent Beach Tower is a chlorination control unit in the outfall system of Asplund Wastewater Treatment Facility. Since construction in 1973, the site of the Effluent Beach Tower has undergone substantial rates of erosion. AWWU identified the site as a slope stability concern and hired Seawolf Engineering to conduct an environmental study on the area. Objectives requested by the client included:

• Review structural integrity of the Beach Tower and effluent piping in the vicinity of the tower
• Provide information documenting rates of bluff recession and beach deflation to guide development of remedial solutions
• Provide bathymetric comparisons to evaluate nearshore deflation and erosion versus prior studies
• Detail wave, water level, and current modelling to examine the coastal area of the tower structure.
• Define the littoral cell to identify the area of influence that could be affected by the placement of erosion controls structures.
• Research, review and incorporate previous studies and data compiled by other agencies identifying ocean patterns and erosion rates of the area, as applicable.
• Provide a draft and final report which include finding from the study and provide a list of recommendations for rehabilitation.
• Prepare initial cost estimates for recommended methods of rehabilitation and erosion control.

The Beach Tower team determined the bluff at Point Woronzof was receding approximately 2 feet per year and the beach deflated 0.2 feet per year, on average. They based their findings off of one-dimensional wave analysis, tidal current modelling, historical bathymetric data, geotechnical data, and incorporated review of prior studies. The structural integrity of the Beach Tower and associated piping was also evaluated for meteorological and hydrodynamic loading and for predicted rates of bluff recession and beach deflation. The beach tower team investigated the feasibility of alternatives for erosion response such as beach nourishment, revetments, and in-water structures. Continued erosion of the Point Woronzof bluff is expected to damage resources such as the Tony Knowles Coastal Trail, Ted Steven’s International Airport’s Runway 33, Point Woronzof Drive, Point Woronzof Park, CEA transformers, and AWWU’s sampling station. Throughout the course of the senior design project, the team develop and proposed  a concept of using both revetment and beach nourishment to stabilize the bluff and prevent any future damage to existing infrastructure.

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