Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/282830
OPERATIONS ILLUSTRATED AGGREGATES MANAGER Voices of Experience Scott Jorns Wendy Schlett ▼ ▼ A lthough timelines show work on the ornton Reservoir starting in 1998, "the project actually took hold around 1994," recalls Sco Jorns, quarry manager for Hanson Material Service's ornton Quarry, located on the south side of Cook County, Ill. "at's when we started calculating reserves, and we determined what was needed to turn the north quarry into a reservoir." Mining had previously stopped at ornton's north quarry in the late 1980s, at a depth of 150 feet. For the reservoir's capacity purposes, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) needed additional reserves, which required the purchase of property north of the original wall. Work began on the tunnels in 1997, and as part of an agreement between quarry owners and MWRD, ornton Quarry began to process an average of 5 million tons per year of dolomite limestone to remove the 76 million tons required for the reservoir. "We produced 6.9 million tons in 2000, with our biggest year being 2006, when we produced 7.3 million tons," Jorns says. e work that progressed on the north quarry created three separate benches, at a depth of 150 feet, 75 feet, and 115 feet, for a total depth of 340 feet. e reservoir is 1/2-mile long from east to west, 1/4-mile wide from north to south. "We had to mine to the correct depth for the tunnels that tie in on the east and bring stormwater into the temporary reservoir," Jorns says, explaining that a 32-foot-diameter tunnel on the north side will bring stormwater overﬂow out of the surrounding suburbs. A south tunnel will bring in overﬂow water from orn Creek. "A temporary reservoir in our west quarry currently takes overﬂow from orn Creek, but that tunnel will be plugged when the north quarry goes online with the reservoir (in 2015)," he adds. Mining has continued in the west quarry, even though it was being used as a temporary reservoir. "We monitor the levels of orn Creek, and we know when it's rising. If it reaches 14 1/2 feet, we know it will ﬂood. Before the gates are opened, verbal conﬁrmation that the quarry is evacuated is given to MWRD. But we've been concentrating so hard on mining out the north quarry, that work in the west quarry has been minimal," Jorns says. e ornton Quarry is one of the largest quarries in the world. "People driving on I-80 only see half of it. It's 400-feet deep, but only a small portion of the quarry has been mined to that depth, plus the underground reserves remain untouched," Jorns says. "My kids will be retired before mining is complete at this site." "T he best way for aggregate companies to solve a need the way the ornton and McCook quarries have is to work with community and planning commission leaders to identify needs and solutions," says Wendy Schle, senior sustainability manager for Sustainability Research Group, based in Grand Rapids, Mich. "at's the best way to ensure that everybody beneﬁts in the end." Although ornton and McCook quarries are among the world's largest aggregate mines, a smaller site may also realize beneﬁts as a reservoir for stormwater overﬂow or a community's water supply. If a mining company speciﬁcally targets water storage as a possible reclamation goal, Schle says, it needs to consider how close it is to completing the lifecycle of the mine. "Otherwise, if mining is still ongoing, there has to be a way to separate the pits, like ornton has done," she says. In situations where quarries operate within a large spread of land, however, Schle says that most of these sites already have stormwater ba- sins to contain their own stormwater runoﬀ. "If they are mined out already, then the basins are potentially available for use for the community's stormwater control," she says. Additionally, if an older quarry is closed and ﬁts the criteria, landowners and community leaders might ﬁnd beneﬁcial use for it as water stor- age. "For instance, Atlanta has a project in the works to reclaim an old quarry — already past its mine life — as water supply storage to capture as much water as possible for use during drought periods," Schle says. Each mine site is diﬀerent, and the site's mineral makeup may preclude using it for water supply storage. Likewise, each community has dif- ferent needs. e more involved a producer is with the community, the more the community's needs will become apparent. A producer may already have a reclamation plan in place for a site, but oen can alter it to ﬁt a community need. "Reclamation is handled on the local level," Schle explains. "It's submied as part of the permit, but there should be the ability to amend part of that plan — if a beneﬁcial use arises. You'd have to go through the township public review process, but especially if it could beneﬁt the community, it shouldn't be a challenge to obtain (a revision) to the original mine plan." Dual uses of reclaimed mining sites are also possible, especially when targeting the site for water storage, says Schle. e Atlanta site will use the surrounding area for nature conservation as a park, in addition to water conservation. "Mines oen create unique habitats for wildlife, such as rock outcroppings for birds," she says.