Field Tripping in the Pits
AGGREGATE (SAND, CRUSHED STONE, AND ROCK) is the most mined material on earth, and the pits created by its extraction are all over the place. Every city has a network of them, since they are the source of the primary material for roads, foundations, and anything made of concrete. They are often massive, even a few miles wide, and dramatic, with abrupt cliffs, colorful ponds, complex conveyors, and conical piles of sorted material. Yet they are generally overlooked, unseen, and, certainly, rarely appreciated by the public.
For these reasons and more, the CLUI has been engaged in a continuous investigation into these quotidian extractive landscapes–how they work, where they are, and what happens to them once they are mined out. This fall, the CLUI was invited to work on the subject with a landscape architecture class at Ohio State University. The class, directed by Ben Loescher of the CLUI and their professor, Jason Kentner, will generate a publication about their findings.
The Ohio State project focuses on the belt of Columbus Limestone, the most useful form of aggregate in the region, which runs underneath the state’s capitol of Columbus (home of Ohio State University), and continues north to Lake Erie, where it continues to be mined from pits on islands that extend beneath the level of the lake.
The first of two field trips, conducted in October 2011, looked at the full range of local pits, from active and expanding ones, to long since closed ones which have been turned into housing developments or parks.
To get oriented, we started the day with a visit with the curator of the geology museum on campus, Dale Gnidovec, who gave us an overview of the underlying strata. He described the history of the landscape of Ohio, starting with the formation of the earth itself, followed by the global events that transpired to build up the layers beneath us. Geology, as Mr. Gnidovec eloquently stated, is the book of earth time. The past begins with the oldest, at the bottom, and works its way up to the surface, to now.
Once stratigraphically and temporally oriented, we felt a fresh, renewed sense of awareness of our place on the surface of the planet. With this clarity we headed out for an intense day of encounters.
Onto the chartered bus, and to the largest active quarry in the region, the Columbus Limestone pit on Jackson Pike, 15 minutes from campus, and just four miles south of downtown. At the gate we were met by Jamie Sturgeon, public relations officer for the Shelly Materials company, which operates the pit. She escorted the bus onto the site for outdoor briefings with the pit’s designers, operators, managers, and regulators.
Shelly Materials is the principal aggregate supply company in the region. It started as a local construction company in 1938, specializing in roads when the post-WWII boom set in. The company now operates in Ohio, Indiana, and West Virginia, and has 24 subsidiaries with 41 asphalt plants, 28 redimix concrete plants, seven rail depots, four liquid terminals, and 45 aggregate operations.
As is the norm in these days of consolidation and globalization, Shelly Materials is owned by a larger company, Oldcastle Materials, a nationwide supplier of aggregates, asphalt, ready mixed concrete and paving services, with 1,200 locations, which, itself, is owned by CRH International Building Materials Group, a global construction material supplier, headquartered in Ireland, with 75,000 employees around the world. A conglomeration of aggregates.
The Jackson Pike pit is about a square mile in size, and with surrounding processing and storage areas, covers a site nearly exactly as big as downtown Columbus. It is on the Scioto River, the main waterway through town, and as a result needs to run pumps continuously to stay dry. Three pump stations in sumps below the bottom of the pit are equipped with 15 pumps that remove 20 million gallons of water per day. The water discharges into ponds, and into the river, and is used to irrigate some landscaping operations nearby.
The main product produced there is known as “state rock.” This is the material that meets the specifications required by the state’s road builders. To be state rock, the aggregate (in this and most cases) limestone needs to meet standards of durability, compressibility, and uniformity as specified by state and other agencies, in order to be determined to be suitable for road construction. This is an important determination, and one that affects the life and existence of quarry operations, since road building is one of the largest single use of aggregate, and the higher grade rock is more valuable. It is used in road beds, as well as asphalt, which is 95% aggregate.
If the rock does not meet these standards, then the material is considered “commercial rock,” available for other uses, as determined by the regulations and requirements of other commercial construction industries. The American Society for Testing and Materials is one source of specs for determining what quality, size, and shape of rock can be used in different applications.
As with most hard rock aggregate pits (as opposed to sand pits), the material is blasted out from the solid rock strata along vertical working faces. Front end loaders scoop up the loosened, random-sized material and put it in dump trucks which take it to the crusher, which grinds the rock to a specified dimension. Different dimensions and mixtures are used for different uses, ranging from less than half an inch diameter, for concrete, to several inches, used in riprap. Of the 40 employees at the pit, most work at the crushing and sorting operation.
With no navigation possible on the Scioto, and no rail terminal here, all the material leaves the site by truck, at a rate of up to 800 trucks per day. Most trucks can hold 21 tons. Selling for between $5 per ton (for ungraded #9 gravel) and $10 per ton (for washed #2 gravel) it is clear that the largest expense in this business is for transportation, and the further the material has to be moved from the pit, the more expensive the project becomes. This is one reason why cities exist. As cities grow, the close-in aggregate pits become surrounded by development. This makes expansion difficult physically, as new buildings surround the pits, and also difficult due to pressure from people in the encroaching communities, who complain about unsightliness of industrial operations and the traffic, dust, and noise they produce. The proximity to the urban center, so highly valued, can eventually become a liability that forces many to shut down once they have mined out their layer of readily available limestone, or even before.
Some quarries are finding another solution–going underground. If the mineral rights of property adjacent to the pit can be acquired, then the layer of rock can continue to be mined by tunneling into the vertical wall, leaving the surface property undisturbed. Ten years ago there were around 200 underground aggregate rock mines in the country. Now there are more than 300.
They have just started one here at Jackson Pike, extending the quarry northwestward by tunneling underneath land owned by the county. Shelly Materials found that the operating cost of extracting gravel from underground was nearly the same as from a pit, requiring just the initial purchase of around $150,000 in new drilling equipment. And because underground mining is regulated at a federal level, alot of the local regulations and state permits required for surface mining are not applicable, which simplifies, expedites, and economizes the process.
Once we had completed our tour and discussions at Shelly Materials, we headed back up from the pit level, onto the surface plane, to look at some examples of pits that have shut down and been filled in. We didn’t have to go far, as this southern part of the city along the river is the most heavily excavated. The area immediately north of Shelly’s Jackson Pike pit was deeded to the city of Columbus in 2007 for use as the city’s main car impound lot, a large-scale marginal use typical of such post-industrial lands. Some of the fill used to level the site came from a waste incinerator, which brought up some contamination issues. They were solved not by removing the material, but by having the official flood plain boundary moved instead.
Big empty pits on the edge of the city are often simply too tempting to not fill with unwanted waste. Not that long ago, in the years before environmental regulations required lining and isolating landfills from watersheds, gravel pits and marshes were where urban trash went. Across the road from the Jackson Pike Pit is a pit that was filled with trash, known as the Model Landfill. By the time the landfill was closed, it contained five million tons of waste, and was a mound more than 60 feet tall–the highest ground point in the region.
The landfill was operated by the Solid Waste Authority of Central Ohio (SWACO), which began to work with the contamination issues at the site after closure, by installing wells to collect leachate and slow the migration of contaminants into the groundwater, and installing gas pipes to collect and burn the methane. The landfill was also covered in a less permeable clay cap to reduce the amount of moisture flowing into and out of the buried waste. Development possibilities for the grounds are limited, due to the unstable landfill grounds and the fragile impermeable layer under the topsoil. One use that was considered possible was a golf course, so to help defray costs, one was built. It opened in 2000–the first golf course on a landfill in the state.
The course was designed by Tim Nugent, of Nugent Golf Inc, a golf course design firm who has completed several landfill-to-golf course projects. This is a “links style” course, meaning that it has no trees, as trees would damage the clay closure cap. The 185 acre course has over 6,900 yards of manicured bentgrass tees, fairways and greens, and dozens of bunkers. The major vertical obstacles are methane vents, fenced off with signs warning of flammable gas. Located next to the freeway, and with a good view of downtown, the course is moderately priced and moderately popular. Since composting waste generates heat, the ground is slightly warm, which, in the winter, means the course has more snow-free days than others in the area. Another unique feature is that the course actually has 19 holes–one is kept in reserve for when any of the standard 18 are out of commission for repairs due to subsidence issues. These points and more are conveyed to the group as we are shown around the site by the course’s manager, Charlie Castle, who led the group of 20 people, including the bus driver, as well as two representatives of the Ohio State Department of Natural Resources’ Division of Mineral Resources Management, who joined us at the last stop, traveling in a convoy of electric golf carts. After the tour, we headed into the Ryder Cup Grille (“the 20th hole?”) for a lunch of hot dogs and apples.
After lunch, the group boarded the bus again and headed to the other cluster of pits around Columbus, also located along the Scioto River, four miles upstream of downtown. This area is less industrialized than the cluster downstream, and is more impacted by the encroachment of residential development. Only one pit remains active.
We arrive at Quarry Lake Drive, where a gated community called the Quarry Apartments opened in 2005, built around a now flooded former quarry, which has been incorporated into the development as a scenic recreational focal point. We stopped across the street from the development and climbed a small and distinct mound. This is the Shrum Mound, a Native American mound believed to have been built 2,000 years ago by members of the Adena culture, and one of the few remaining conical native burial mounds left in the region. It’s a nice reminder that Ohio residents have a good history of heaping and mounding as well as excavating. From the top of the mound it became clear that it is located on an isthmus of sorts, a narrow strip of surface-level land between two former pits, one turned into the housing development, and another, nearly a mile long, hemmed in by McKinley Avenue and the railroad tracks, and slowly filling up with water. A native mound at the fulcrum between two deep gouges. We imagine what a nice cross-sectional relief drawing this would make.
A mile north, further up the river, we approach the operating part of the Marble Cliff Quarry, which once covered much of the area, but now is limited to a half-mile square pit, the last of the active pits in this area. It is operated by Shelly Materials too, and the company has had to work extensively with the encroaching neighbors to continue here. A new entrance road was constructed at great expense to route trucks more directly onto commercial streets. The mile-long road wraps around the edge of the quarry property, and is lined with trees that obscure the pit.
At the office we meet up with Mike Matoszkia, Shelly’s Area Operations Manager, and tour the pit. This is one of the more historic quarries in the state. It started out as a dimension stone quarry in the mid 1800s, and was the source for limestone for the State Capitol building, as well as limestone aggregate for Ohio Stadium and large portions of the Columbus freeway system. Many older houses in the area have stone foundations and window sills from this pit. It was operated for years by the Kauffman family, with as many as 400 workers on site, including at times inmates, breaking rocks by hand. The site was originally considered favorable because it had less than 10 feet of glacial overburden on top of a 250-foot deep bed of Silurian and Devonian Limestone and Dolomite. But after more than a hundred years the original formation has been nearly exhausted, and no highly prized “state rock” remains. They used to mine as much as 2 million tons a year here. Now they do around 400,000 tons, mostly construction-grade aggregate for asphalt and concrete used in residential and commercial developments.
Though Shelly Materials operates the quarry, the site is currently owned by the Specialty Restaurants Corporation, based in Orange County, California. The company operates more than a dozen restaurants and banquet facilities around the country, mostly along waterfronts, such as the Reef, on Long Beach Harbor, Brady’s Landing restaurant, on the ship channel in Houston; the Rusty Pelican, on Biscayne Bay in Miami; and a pivotal site in Columbus too, the River Club Restaurant, which dominates the confluence point of the Olentangy and Scioto rivers, and overlooks the downtown skyline. The company seems to be curating vistas, or at least considers the view as an important element of the dining experience. We’re not sure if they have plans for the marble Cliff Quarry or not, but with its tall highwalls and location next to the dam on the Scioto, it will make a nice deep lake, someday.
The last stop of the day was at the Darby Bend Lakes area of the Prairie Oaks Metropark, an example of a former quarry site returned to public use. Located eight miles further west, along Big Darby Creek, this group of quarries closed many years ago, and the site is slowly being returned to a “natural” condition by the State of Ohio Metroparks division naturalists, including Tom Cochran, who meets us at the site. The stripped topsoil and heavy compaction of the quarry days are still evident in the middle of the park, where a barren and hard denuded look prevails. The ponds, not yet surrounded by the planned native vegetation, look stark and decidedly unnatural. The fact that some are a hundred feet deep and have pallets, Christmas trees, and plastic items tossed in there by the parks department to create habitat for the native fish they are stocking them with now, somehow distances the site even further from its intended naturalness. Once we learn that one of the ponds has a designated dog swimming beach, but otherwise swimming is not allowed in the park, and that the park is the site of WAGfest, an annual dog festival with an attendance of more than 1,500 (dogs), it makes sense: it’s not really a park for people, but it’s a perfect park for people with dogs.
The field trip heads back to campus in the fading light, thinking that maybe the best use for an abandoned quarry is as an abandoned quarry. A few weeks later, on a second trip, exploring the aggregate realm at the top of the state, this sentiment was reinforced. But an account of that will wait for another day. ♦