City of Oneonta Water Supply Dams

City of Oneonta

The City of Oneonta’s main water supply is provided from two reservoirs which impound the Oneonta Creek a short distance upstream of the city. Each dam consists of an earthen embankment section with a concrete spillway. Both were constructed over 110 years ago and are currently identified as Class “B” (Moderate Hazard) structures. In accordance with NYSDEC Dam Safety Regulations, an initial Safety Inspection was required for each dam. The City of Oneonta hired C.T. Male Associates to conduct the Safety Inspections and to perform an Engineering Assessment for each dam.  As part of the Engineering Assessment, C.T. Male Associates performed a review of each dam’s current hazard classification and, where necessary, provided recommendations for any changes.

A subsurface investigation program was performed as part of the Engineering Assessments and consisted of the advancement of test borings and test pits at each of the dam locations. Samples were recovered from both the embankment and foundation soils for laboratory testing as well as estimation of the soil strength parameters for use in stability analyses. During advancement of the test borings along the crest of each dam, falling head permeability testing was performed at select intervals in order to estimate the permeability of the embankment soils upstream of the dam’s central core walls.

In addition, at the request of the City, C.T. Male Associates has reviewed the dam’s current Inspection & Maintenance Plans and Emergency Action Plans. Recommendations were provided to the City for updating and modifying each of the plans to suit current operations as well as conditions downstream of the dams.