The Lake Iosco Dams were constructed in 1923 for the purpose of impounding a 75-acre recreational lake. Irish Brook Dam and Post Brook Dam are both Class I, High Hazard structures, which means that there is the potential for loss of life if either dam fails. While the community had been maintaining the two dams, engineering studies indicated that both Irish Brook Dam and Post Brook Dam did not meet current Dam Safety Standards for overturning and sliding stability. This is a common and expensive problem with older gravity dams since it meant that both dams needed to be rehabilitated to meet the current standards. Civil Dynamics was engaged by the Company in 2004 to address the problem.
Given the large cost to a small community, it was important for our first task to include the evaluation of all the possible alternatives to improve the stability of the two dams. Various alternatives were considered, specifically, post-tension anchoring, roller compacted concrete buttresses, grouted riprap buttresses and cast-in-place concrete buttresses. Civil Dynamics concluded that a cast-in-place concrete buttress would provide the necessary stability and long-term durability as well as being the most cost-effective and aesthetically-pleasing option. Civil Dynamics then revisited the stability analysis in detail to optimize the shape and size of the buttress. During this task, it was concluded that a stepped buttress would be the most cost effective as it significantly reduced the cost of forming the concrete. Engineering analysis of the step geometry was conducted to evaluate various step dimensions and the resulting flow over the steps during an overtopping event. The desire was to have the water cascade from one step to another.
Civil Dynamics prepared construction plans and specifications, and performed construction inspection for two dams. The work was completed on time and within budget.
BEST LAKE DAM
Lake and Dam Restoration
: Borough of Watchung
: Watchung Borough, Somerset County, New Jersey
: Somerset County Land Development & Planning Award for 2008
Civil Dynamics was selected to conduct a feasibility study for both dredging Best Lake and rehabilitating Best Lake Dam. We then were selected to conduct the Design and Permitting Phases and then perform construction inspection for this project. In addition to the need to increase the spillway capacity, there was the need to rehabilitate the dam and spillway due to their deteriorated condition. Specifically, in August 2004, Borough personnel observed significant seepage through the embankment near the right training wall of the spillway. Emergency repair work in this area by Borough personnel led to the discovery of large voids through the embankment caused by internal erosion of the embankment soils. It was concluded that a major rehabilitation of the dam embankment was necessary to prevent continued deterioration and possible failure. Also, the spillway was a masonry structure that was in need of rehabilitation since the last major repairs were in the early 1970’s.
The lake setting is unique in that it is located in the center of town. To address the Borough’s concerns with the appearance of a large “new concrete” structure, we designed a new reinforced concrete spillway with all exposed concrete surfaces (spillway and training walls) to be constructed using manufactured “formliners” inside the concrete forms. Following staining of the concrete using three different colors, the new spillway had the appearance of an old stone masonry wall that matched the nearby historic buildings.
Civil Dynamics began work on this dam located in the middle of the Richard Stockton State College campus in 2002. The dam did not meet New Jersey Dam Safety Standards and was damaged during a storm in August 1997. Specifically, the spillway capacity was inadequate and the dam was overtopped and damaged. The design phase of work initially focused on a large new circular spillway structure along with a parapet wall to prevent overtopping during the design storm. But we subsequently concluded that the complexity and cost of the rehabilitation had reached a magnitude that was no longer appropriate for the size and setting of the dam. Therefore, we revised the design concept to include a smaller, more economical spillway along with overtopping protection on the dam to allow the dam to function as an emergency spillway. The construction of the rehabilitation was completed to the satisfaction of the College in the fall of 2005.
SENECA LAKE DAM
Reconstruction following Breach
: Seneca Lake Club, Inc.
: Sparta Township, Sussex County, New Jersey
: New Jersey American Concrete Institute Merit Award for 2005
The Seneca Lake Dam was constructed for the purpose of impounding a 23-acre recreational lake. The existing spillway was seriously undersized to handle large storm events.
During the storm of August 12, 2000, the spillway could not handle the flows and the earth dam overtopped. The overtopping of the earth dam resulted in the complete failure of the dam. The dam breach was 40 feet wide by 10 feet deep, resulting in the complete draining of the lake. Loss of the lake was devastating to the community and they immediately began plans to rebuild the dam and regain the use of their lake.
Civil Dynamics prepared construction plans and specifications, and performed construction inspection for this project. The project scope consisted of the rehabilitation of the existing earthen embankment dam and construction of a new concrete semi-circular spillway and discharge channel. The work was completed on time and within budget.
The City of Newark owns and operates 11 reservoirs and 16 dams for water supply and Civil Dynamics has been providing the City with water resources and dam engineering services since 1986.
The largest dam is the Charlotteburg Dam which was constructed in the 1960’s. The dam is a 100-foot high concrete gravity structure with a 200-foot long spillway and a 5-foot high Bascule gate. Civil Dynamics designed general repairs to concrete surfaces and major renovations to the mechanical components (gates, valves and controls). The work was completed in 2003.
Civil Dynamics has continued to provide dam inspection services and we also prepared a comprehensive Emergency Action Plan for all of the dams in the Pequannock Watershed. We recently prepared Operations and Maintenance Plans for the larger dams and assisted the City in conducting training for their employees.
Civil Dynamics was responsible for the 2006 Formal Inspections and 2008 Regular Inspections of the two large high hazard dams at the Boonton Reservoir owned by the City of Jersey City. Boonton Dam is a cyclopean concrete gravity dam that is 2,100 feet long and 115 feet high. Parsippany Dike is an earth embankment that is 3,200 feet long and over 30 feet high. Both dams qualify as “Large” dam structures and require inspection by a Professional Engineer with at least 10 years of large dam experience. Civil Dynamics is one of the few firms with personnel that exceed this requirement.
MASKELLS MILL POND DAM
Repair and Rehabilitation
: State of New Jersey, Division of Fish and Wildlife
: Maskells Mill Pond Wildlife Management Area, Salem County, New Jersey
Civil Dynamics conducted the necessary studies and design of the remedial repairs and improvements to bring the Maskells Mill Pond Dam into compliance with the New Jersey Dam Safety Standards. The existing spillway structure was completely rehabilitated and a new auxiliary spillway was added. General site/parking area improvements were also included. The rehabilitation of Maskells Mill Pond Dam was completed in late 2009.
HIGHLAND LAKE DAM
Repair and Rehabilitation
: Highland Lakes Country Club and Community Association
: Vernon Township, Sussex County, New Jersey
: New Jersey American Concrete Institute Honorable Merit Award for 2001
The Highland Lakes Country Club and Community Association owns five lakes and dams, all of which had to be rehabilitated to meet current Dam Safety Standards. Civil Dynamics performed design studies, prepared construction plans and specifications, and performed construction inspection for all five dams.
The largest dam at the main lake was rehabilitated in 2001 and received the New Jersey American Concrete Institute Merit Award.
Civil Dynamics was initially engaged by the property owner to conduct an evaluation of the probable cost to rehabilitate this small dam to bring it into compliance with Dam Safety Standards. Our evaluation of the existing structure led to a decision to permanently breach or decommission the dam so that the proposed development would not have the long-term liability associated with the dam. As part of the decommissioning of the dam, the new outlet structure was designed to meet the requirements of the New Jersey Dam Safety Standards and assist with stormwater management of the proposed development in accordance with Residential Site Improvement Standards. The decommissioning of the dam was completed in early Fall 2005. The completed breach successfully managed heavy rains in October 2005 without any problems.
GRAFTON LAKES STATE PARK DAMS
Studies and EAPs
: New York State Office of Parks, Recreation & Historic Preservation
: Grafton Lakes State Park, Rensselaer County, New York
Civil Dynamics recently completed a three-year contract with the New York State Office of Parks, Recreation & Historic Preservation to provide services on their dams.
Work included conducting hydrologic and hydraulic evaluation of four dams including the large Martin Dunham Reservoir Dam in Grafton Lakes State Park.
Civil Dynamic also developed the design of the major rehabilitation of the Martin Dunham Reservoir Dam to increase the spillway capacity and address other dam safety deficiencies. We were also responsible for the rehabilitation design of the smaller Mill Pond Dam to address general dam safety deficiencies.
Civil Dynamics was responsible for the evaluation and the development of rehabilitation alternatives for Sebago Lake Dam, which is a large high hazard dam in Harriman State Park for the New York Palisades Interstate Park Commission. Work later included development of the Emergency Action Plan and inundation mapping in accordance with the New York State Department of Environmental Conservation Dam Safety Regulations.
Civil Dynamics also conducted hydrologic and hydraulic studies, including dam break modeling, and developed Emergency Action Plans with inundation maps for Lake Tiorati Dam and Little Dam Lake Dam in accordance with the New York State Department of Environmental Conservation Dam Safety Regulations.