Elmhurst Dam

Project Name: Elmhurst Dam Rehabilitation Project

Project Location: Roaring Brook Township, Pennsylvania

Owner: Pennsylvania American Water Co.

GC: Charles J. Merlo

Project Revenue: $1,400,000.00

Project Start and End Date: 2014- 2017

Summary:

The 117-year old Elmhurst Dam, is a 64-foot (ft.) high, 380 ft. long composite earth-fill embankment that provides drinking water and flood protection to the city of Scranton, PA.

The Challenge:

The dam upgrades included improved stability and drainage systems to better collect seepage and increase the dam’s ability to withstand floods to meet new state Department of Environmental Protection standards.

The Elmhurst Dam rehabilitation consisted of the excavation for a new stepped spillway along the right abutment of the existing dam, and excavation and repairs to the existing spillway. Construction of an earthen berm along the top slope of the existing dam was also required. The deepest excavation extended 55 ft. below the normal pool of the Elmhurst Reservoir.

The Solution:

To obtain the required drawdown for construction on the dam, griffin installed 29 primary 8-inch diameter till wells with an average depth of 44 ft., And 13 primary 12-inch diameter primary outwash wells with an average depth of 62 ft. These wells were installed in the right abutment of the existing earthen dam.

The initial design also included the potential installation of an additional 24 secondary 8-inch diameter till wells, and 2 secondary outwash wells. After installation and testing of the primary till and outwash deep wells, griffin coordinated with the engineer and contractor to install four (4) of the secondary outwash wells.

The Griffin Difference:

The deep well dewatering system controlled groundwater and allowed construction to be conducted in a safe and efficient manner. Griffin timed the schedule of construction to coincide with the seasonal low pool levels of the Reservoir. Griffin worked seamlessly with all necessary parties and complied with all dam safety requirements to complete this job.