Upper Van Horn Dam – City of Springfield Phase II Engineering Evaluation & Alternatives Analysis

Challenge

Upper Van Horn Reservoir Dam is an Intermediate sized, Significant Hazard potential, earthen embankment structure which is approximately 905 feet long with a maximum height of 32 feet. The condition of Upper Van Horn Reservoir Dam has been rated as “Poor.” The Poor condition rating has been assigned to the dam in Phase I Inspections conducted between 2009 and 2017, due to the presence of large trees on the embankment slopes, animal burrows, uncontrolled seepage, concrete condition issues, no operable low-level outlet or provisions for emptying the pond, and no available design or post-design analyses concerning seepage or embankment stability.

The crest of the dam is approximately 50 feet wide and supports Armory Street, a major City arterial roadway. The dam is in series with the downstream Lower Van Horn Reservoir Dam that was recently rehabilitated with Dam Repair grant assistance. Both dams are upstream from residential homes, commercial buildings, a railroad corridor, Interstate 91, and Baystate Medical Center, the leading medical and emergency treatment center in western Massachusetts. The dam is owned by the City of Springfield and operated/maintained by the City’s Department of Parks, Buildings, and Recreation Management.

Solution

GZA assisted the City of Springfield with the preparation of a successful MA EEA Dam and Seawall Repair and Removal Grant Application, which yielded $84,000 in state funding at a 25% match to assist the City with the preparation of a Phase II Engineering Evaluation and Alternatives Analysis for the Upper Van Horn Reservoir Dam, located along Armory Street, a busy City arterial.

GZA’s services included the development of a Phase II Engineering Analysis Program and Alternatives Analysis with specific tasks, including:

• Review of all available information regarding the dam (historical drawings and reports, past inspection reports, survey information, etc.)
• Detailed visual inspection of the twin barrel culvert that serves as the primary spillway for the dam 
• Study of the former pond outlet, including field review for the presence of the former outlet and camera investigation of the former outlet conduit to understand its current condition and function as it passes through the dam embankments
• Subsurface exploration program including multiple test borings and geoprobes to characterize embankment materials and review the potential for a core wall
• Topographic mapping of the dam area
• Wetland delineation of the dam area and preliminary wetland report to be used in permitting
• Hydrologic and hydraulic analysis of the spillway
• Seepage and stability analyses
• Development of an alternatives analysis
• Development of a preferred conceptual rehabilitation solution
• Preparation of a Phase II report, summarizing all work completed and needed permits for the conceptual rehabilitation program

Benefit

GZA completed the assignment on time and on budget and later assisted with another successful Dam and Seawall Grant to pursue funding for design and permitting.