Pennsy Supply - Quarry report warns of sinkholes
Mar, 04 2004
Quarry report warns of sinkholes
(Pa) A hydrogeologist hired by a citizens' group opposed to the proposed St. Thomas Quarry warns of sinkholes and far-reaching water problems from the quarry.
Thomas Aley, director of the Ozark Underground Laboratory in Missouri, is to send his report to the Department of Environmental Protection. Citizens have until Friday to make comments to DEP about the application by St. Thomas Development Inc., a subsidiary of DePaul Development Inc. in Blue Bell, to quarry 174 acres in St. Thomas Township.
DePaul's application should be considered incomplete because it is not based on karst geology -- limestone geology characterized by cracks, caves and sinkholes, according to a draft of Aley's report. The quarry would be dug in karst geology.
The edge of the quarry would be about 1,200 feet from the St. Thomas Elementary School and St. Thomas Township Volunteer Fire Company and about 520 feet from U.S. 30.
"We do not want to see a sinkhole open up at the school," said Mike Urban, vice president of the citizens group Friends and Residents of St. Thomas Township (FROST). "What we're looking to do is to protect the village of St. Thomas. There may be places where (quarrying) is not appropriate, and this is one of them."
DePaul's application reported there was no evidence of sinkholes on the property.
Fran Calvarese, FROST president, said two can be seen from U.S. 30 and several are located on a U.S. Geological Survey map of the area.
Sinkholes can develop as mining begins and water is pumped from the bottom of deeper quarries, according to Aley.
Karst limestone is riddled with holes that may be filled with loose stone and soil. As the water supporting the loose fill is drained, the fill collapses and a sinkhole is formed.
A 95-foot-deep limestone quarry near Talladega, Ala., caused a spring about a mile away to cease flowing, according to Aley. A dye test linked the quarry to the spring. About 2,000 sinkholes, some as large as 30 feet in diameter and 50 feet deep, opened on an adjacent 1,000-acre tract. Cattle fell in the holes, and two were killed.
It would not be unreasonable to test the quarry site for openings that could develop into water conduits and sinkholes, according to Aley.
Properties outside the 5,509 acres considered by DePaul's application would be affected by pumping water from the bottom of the quarry, Aley said.
Water must be pumped from the bottom of a quarry pit when it hits groundwater so mining can continue. Pumping at St. Thomas must begin at a depth of about 50 feet, or about 12 years into the 100-year life of the quarry, according to DePaul's application. The quarry would go as deep as 300 feet, and up to 2 million gallons of water a day would be pumped from the pit.
Aley said DePaul's geological model is flawed in predicting the effects of pumping. Aley's firm conducted 50 dye tests in limestone deposits at Letterkenny Army Depot and found that water flowed more quickly through the rock than predicted by DePaul's model. Dye tests characterize water flow in karst settings better than models, according to Aley.
The water table is within 30 feet of the surface of the quarry site, according to DePaul's application.
DEP earlier this week approved the application of Pennsy Supply, Harrisburg, to begin quarrying in Penn Township, Cumberland County, near Big Spring Creek. The mine may not go deeper than within 30 feet of the groundwater level.
"Would it be financially viable for (DePaul) to go that route?" Urban asked. "In certain places the water table is very high."
He said FROST wanted to hire a hydrogeologist who was familiar with the area.
The group has about 25 active members, and has been meeting weekly since Christmas, according to Calvarese.
Member donations funded Aley's review. The group anticipates doing more studies and may begin fund raising.
"I have a feeling this is going to be a long-term process," Urban said.
St. Thomas Township supervisors have asked DEP to conduct a public hearing about the quarry application. DEP has not set a date.
Supervisors previously approved a land development plan for the quarry.
They are forwarding their geologist's comments to DEP. Geologist Wallace Koster, Chambersburg, warned of "accelerated sinkhole development in areas including U.S. 30."
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