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Cacapon park dam will handle stronger storms

Upgrades cost $1.7 million

By Kate Shunney

The Morgan Messenger

BERKELEY SPRINGS — Earthen dams at Cacapon State Park’s lakes have not failed during their lifespan at the park, and they’ll be even less likely to after upgrade work on them finishes in the spring.

Excavation and prep work for the $1.7 million project began in September at both the upper reservoir dam and the lower recreation lake dam. Structural work is expected to be largely done by the end of this month, state park officials said last week.

In the spring, contractor Heeter Geotechnical could finish seeding and restoring areas around the two dams that have been disturbed.

A concrete “batch plant” is operating below the lower dam at Cacapon State Park to supply materials for dam upgrades. A concrete “batch plant” is operating below the lower dam at Cacapon State Park to supply materials for dam upgrades. Brad LeslieChief Engineer of the West Virginia Division of Natural Resources, said the move to modify both dams came from a need to make DNR dams meet new structural criteria – a Probable Maximum Participation Storm model.

In other words, said DNR Engineer James Schotsch, the dams must withstand “a greater volume of precipitation and longer duration than earlier design storm models.”

Schotsch said when work on the dams is done, both will pass that storm test “without threat of failure.”

“We hope to have the major construction done before hard winter sets in,” said Schotsch.

Recently, as he visited the work site at Cacapon, he said neither dam has failed up to this point.

CCC workers built the lower dam, with a core of stonework, in the 1930’s. An upper section of the stone core was revealed during excavation, but has already been covered again as work accelerates.

A concrete footer has been poured into the crest of the reservoir lake at Cacapon State Park. It will protect the crest from eroding if water tops the dam during an extreme event. A concrete footer has been poured into the crest of the reservoir lake at Cacapon State Park. It will protect the crest from eroding if water tops the dam during an extreme event. The upper reservoir lake dam was built in the early 1970’s to supply water for irrigating the park’s golf course. Both dam up parts of Indian Run, a tributary of Sleepy Creek. The two dams are located roughly threequarters of a mile apart, said Schotsch.

The upper dam is 550 feet wide, 36 feet tall and holds back six and a half acres of water, according to Schotsch.

The lower lake dam is 366 feet wide, 34 feet tall and holds back six acres of water.

DNR’s Leslie said funds for the dam modifications come from the Wildlife Division of the DNR. Officials said the money has come from royalties from oil and gas extraction across West Virginia. Because both dams are at lakes designated for fishing, money from the wildlife division can be used for the work.

Civil Tech Engineering, Inc. is the design consultant for the work and does on-site inspections.

Schotsch said the dam modifications were designed in 2010. The project has been waiting for funding.

Of the project budget, Heeter Construction will be paid $1.69 million for construction work. Design, permitting and administrative costs add up to $175,000, according to DNR officials.

Lower dam gets “armor”

The construction sites at both dams have been busy for two months. Visitors entering the park immediately see a temporary concrete batch plant in operation at the lower dam. Contractor Heeter Geotechnical has leased the equipment, which makes batches of special concrete. That concrete, which is drier than normal, was spread by bulldozers in horizontal layers, and then compacted by a roller. The stacked layers form an “armor” on the downstream slope of the dam that will protect it in the case of an overflow, said Schotsch.

“In an extreme event, the water will overtop and the whole dam becomes a downstream spillway,” he said.

A foot and a half of soil will be added to the dam slope and it will be planted in grass.

A concrete “apron” is also being built at the bottom of the stone-faced portion of the dam known to engineers as the “spillway.”

Schotsch said the bottom of that spillway had been broken apart over time. A new “stilling basin” design will slow water at the bottom of the stone spillway to reduce the force on the new concrete work at the bottom.

Concrete will be poured at the bottom of the stone-faced spillway. That original stonework will stay exposed, as it has been.

Reservoir dam

West of the main cabin area of the park, work is also going on at the larger reservoir dam.

Schotsch said there are several modifications planned. Workers will install drains to capture water that naturally seeps through the clay-core dam. Plans call for the crest of the reservoir dam to be raised 1.7 feet, increasing the holding capacity of the lake.

Workers will add an earthen buttress at the bottom of the dam for strength. The existing spillway for that dam will be enlarged. At the top of the dam, contractors have poured a narrow concrete footer that will protect the dirt crest in case water overflows the dam.

Schotsch said engineers also designed an emergency spillway that would direct any water that topped the dam in an extreme storm. Water would be directed toward the park road and down the grassy slope along the road, he said.

Rip-rap (large rocks) has been added to the shore of the reservoir to protect it from wave action, Schotsch said.

Contractors will add a hard surface handicapped-accessible trail for fishermen at the upper lake, too.

Neither of the lakes will be restocked with fish until the dam work finishes in the spring, said Schotsch.

Another recreational element to the dam project will be future use of the gravel area that was cleared for a work site below the lower dam.

Once construction equipment and materials are removed, the area may be used for parking and a picnic area, said park officials.

Mature trees cut to make room for the construction site have stayed in the park. Suitable trees could be used for future log restoration in the park, said Schotsch.

The DNR engineering division is now working on designs for interior upgrades at the Old Inn in the park. Their aim will be to update heating and cooling systems so that original lodge building can be used throughout the year, officials said.

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