January 2003 AGGMAN Operations

Glacier Northwest permits and opens a quarry in the bottom of its Snoqualmie Sand and Gravel pit.

Snoqualmie Sand and Gravel is opening a quarry in the bottom of its existing 260-acre sand and gravel pit. The quarry will cover about 60 acres in the eastern part of the pit (lower right side).

After mining about 100 ft. deep over many years, the Snoqualmie Sand and Gravel pit in western Washington hit bottom. But it’s not the end. The bottom of a portion of the sand and gravel deposit has become only the beginning of a quarry. While wheel loaders continue extracting sand and gravel elsewhere in the 260-acre pit, rock drills delineate the extent and nature of the bedrock as they prepare blasts for the developing crushed stone operation. For about the next 50 years, Glacier Northwest, the site’s operator, expects to offer both natural sand and gravel and crushed stone products out of the same mine.
Snoqualmie Sand and Gravel is located about 25 miles east of Seattle on an upland terrace that borders the Snoqualmie River. The Milwaukee Railroad originally opened the pit, according to Ken Johnston, Snoqualmie superintendent. The old rail grade skirts the edge of the property, he says. Glacier Northwest took over operation of the sand and gravel and ready-mixed concrete operations on the site when it purchased Kenmore Premix, which leased the property from Weyerhaeuser.
“When I got here in September 1999, we were producing 1.2 million tons per year of sand and gravel products and about 100,000 cu. yd. per year of ready-mixed concrete,” says Johnston. The operation had encountered bedrock in 1996, but its county grade permit stipulated that drilling and blasting were not allowed. So the company began what became a 34-month-long process of obtaining a permit to open the quarry.
“Because we were an existing pit, we had gone through all the truck traffic and other issues,” Johnston says. “All we asked for in this permit was to be allowed to blast.”
One concern Glacier Northwest addressed was groundwater protection. A groundwater quality monitoring plan developed by Associated Earth Sciences, Kirkland, Wash., includes installation of continuous groundwater level recording devices and data loggers in two wells. One well is completed in the area’s main aquifer; the other well is completed in bedrock. After six months of quarrying, the company will conduct a baseline bedrock fracture characterization analysis and measurements of the quarry face. This is being done to assess the discontinuity of the rock mass.
In addition to the requisite groundwater quality and blast vibration monitoring plans, Glacier Northwest had the challenge of educating neighbors and local government officials about how blasting would — and would not — affect them. “The majority of people don’t understand quarry blasting,” says Johnston. “[They] look at Schwarzenegger movies and think that’s what blasting is, where everything gets decimated and there’s a big fireball. Quarry blasting is so controlled.”
During the permitting process, Johnston arranged a tour of a Glacier Northwest quarry about 25 miles to the south of the Snoqualmie operation. He rented a tour bus and invited everybody within about a half mile of the proposed quarry. “We took them down to the quarry and did a good-sized blast, about 14,000 cu. yd.,” Johnston says. “We bought them lunch on the way back and gave them copies of the seismograph report. It was well worth the time and effort to bring the folks down to actually see what it is.”
For its first blast at Snoqualmie, the company hosted about 30 people — neighbors; city and county officials; and representatives from Weyerhaeuser, the landowner. “When it was over, people said, ‘I thought it was going to be bigger,’” says Johnston.
Prior to blasting at Snoqualmie, Glacier Northwest offered every resident within a half mile of the operation — 63 in all — a preblast survey of their home. The company ended up surveying about half of those homes, Johnston says.
The blasting plan developed for the Snoqualmie site by SubTerra, Inc., calls for use of three seismographs at the following locations during the initial 25 blasts:

The nearest residence, about 500 ft. away from the blast area, receives particular attention. “We do a lot of monitoring now at their house,” says Johnston. “They don’t even know it’s going on. We notify them that we’re going to blast, and they hear the whistles. They’ve come and watched a couple blasts from inside the quarry.”
Initially, Snoqualmie is using a conservative scaled distance value of 70 to calculate the maximum charge weight per delay. After 50 blasts, the company will evaluate the measured scaled distance vs. peak particle velocity relationship and discuss with the county the possibility of reducing the scaled distance value to 55.
Johnston says they are trying to blast 9,000 cu. yd. or more with each shot to obtain representative vibration levels. “Three [blasts] per week is the absolute maximum,” says Johnston. “We’re doing about three per month now. We’ll ramp that up and by next summer we’ll probably be doing two per week.”

Crushed stone and sand and gravel products will be processed and stockpiled separately.

Dual operations
Crushed stone production will ramp up accordingly. It is expected to reach 100,000 tons the first year, increase to 500,000 tons by the fifth year, and maintain that level for the rest of its estimated 50-year life. But the quarry will cover only 60 acres in the eastern part of the 260-acre sand and gravel pit. Sand and gravel extraction is expected to continue to the north and west of the quarry throughout its life.
Rock being mined in the Snoqualmie quarry consists of volcanic andesite lava flows with some interbedded andesite breccia layers. The layers dip to the west due to tectonic movements after their deposition. The breccia layers are weathered, decayed rock that is only usable as fill, according to Johnston. He says that most of these layers can be ripped with a dozer, rather than blasted.
The hardrock layers have variable specific gravities. “We have both a 2.45 and a 2.6 specific gravity,” says Johnston. “I haven’t seen any above 2.6, but we’ve just scratched the surface.”
Mining depth of both the hardrock and the sand and gravel, permitted down to an elevation of 325 ft. above mean sea level (msl), is limited by the level of the area’s primary aquifer. The top of the rock currently is at 520 ft. msl, leaving room for about 195 ft. of excavation.
Snoqualmie’s sand and gravel deposit consists of a “fair amount of 12- to 24-in. cobble,” according to Johnston. There also are some boulders as large as 6 ft. in diameter. “It’s a good pit for crushed material,” he says.
Sand and gravel is mined with a Cat 988 wheel loader in a load-and-carry application feeding a portable Svedala 3248 jaw crusher. About 3,000 ft. of field conveyor transport the material from the working pit face to a surge pile for feeding the crushing and wash plants.
Two Eljay 54-in. Rollercones (one standard, one fine head), an ISC 77 VSI, and four Eljay triple-deck horizontal screens handle sand and gravel processing. A wash plant contains a Hewitt-Robbins double-deck scalping screen, a Seco triple-deck wash screen, a Portec sand classifier with a Spec Select III control system, and a Phoenix Wx-3.0c belt filter press.
The crushed stone plant consists of a portable Telsmith 4248 jaw crusher fed by a Cat 988 wheel loader and a JCI 8- x 20-ft. triple-deck screen. Quarry products are processed separately from sand and gravel materials. “We’re not going to co-mingle the products,” says Johnston. “On the hard rock side, a lot of our market is going to be in rip-rap and [rock wall material]. We will be crushing [to make] 4- to 8-in. and 2- to 4-in. As we grow the business, we’ll put in a closed-circuit cone crusher or two making base materials.”
One area that is shared between the sand and gravel and crushed stone operations is the loadout and truck scales. Snoqualmie ships all of its product by truck over two scales. One of the scales is automated with a JWS system incorporating touch screens and barcode reader cards for use by some of Snoqualmie’s larger customers.
“With the touch screen, they are able to choose what job they are going to and what product,” says Johnston. “It actually runs twice as fast as [using] the ticket window and weighmaster.”
Reaching the bottom of the sand and gravel deposit and the top of bedrock in a portion of its pit was a fortuitous circumstance for Glacier Northwest’s Snoqualmie Sand and Gravel. “The next closest good-sized quarry, above 100,000 tons, is about 17 miles away,” says Johnston. “It’s going to be good for us because of our location. It’s going to expand our business quite a bit.”

Glacier Northwest is permitted to mine to an elevation of 325 ft. above mean sea level. That will provide for about another 50 years of reserves of crushed stone and sand and gravel.

Salem Stone Corp. increases production and reduces hole deviation through drilling equipment upgrade.

Salem Stone Corp. increased productivity at its Sylvatus Quarry near Hillsville, Va., by approximately 50 percent through the use of a new drill.

When a quartzite quarry in Virginia wanted to increase its production and resolve problems with hole deviation, it did so by investing in new drilling equipment. Since then, productivity has gone up by more than 50 percent, they’re able to use the same rig at two other quarries, and their holes are straighter.
Salem Stone Corporation was started in 1983 when Leonard D. Hill bought the Sylvatus Quarry, near Hillsville, Va. The company now also owns six other quarries in Virginia and West Virginia. Three of them produce limestone products, one accostone, and two are sandstone quarries. Salem Stone employs 150 people, 22 of them at Sylvatus. Approximately 75 percent of the stone produced from Sylvatus is used for road surfacing by the states of Virginia and West Virginia. This consists of fractions ranging in size up to 2 in. Other products include three classes of rip-rap, erosion stone for road berms, and stone for walls.

Difficult Drilling
“We do all our own drilling and blasting. The drilling conditions at Sylvatus are really quite difficult,” explains Roger Ramey, superintendent of the Sylvatus Quarry. “The rock is very hard and abrasive and the geology is seamy with vertical fault lines. Hole deviation is a major risk in these conditions. It can result in ‘blow outs’ during blasting, especially if the deviation occurs toward the bottom of the bench. If hole deviation was really significant, we would have to re-drill holes.”

New Drilling Equipment
This risk, together with a desire to increase production, motivated a major upgrade of the quarry’s drilling equipment. “Eight months ago, we had two rigs operating here using T45 drill steel. We decided to replace these and as part of the selection process for the new equipment, we carried out trials of rigs from three different manufacturers here at the quarry,” explains Ramey. “Our drill rig operator, Berlin Cook, had a big say in the final selection. The one he liked best was a Tamrock Pantera rig. We tried out a Pantera 900 using T51 steel, but this really wasn’t big enough for our requirements. So, we finally settled on a Pantera 1100 using the new Sandvik60 drill steel.”

Increased Productivity
One of the major benefits from acquiring the new rig has been a very significant increase in productivity: “I’d say it’s increased more than 50 percent. First, we are now using one rig at Sylvatus, where previously we had two rigs. This has been an obvious savings in terms of machine maintenance and having only one driller,” says Ramey. “Second, we’re now also using the Pantera at two other quarries. Previously, the drilling at these quarries had been sub-contacted. So, again, this has been another obvious savings.”
In terms of service life for the drill steel, Ramey says, “The life of the T45s varied a lot, but I’d say that the average was 8,000 ft. The Sandvik60s, however, are lasting around 14,000 ft. In addition, we have good service from the local Sandvik Tamrock distributor on replacement steel.”
The average drilling rate of the Pantera is 3,000 ft. per week. However, it recently achieved a record week drilling 6,000 ft. in one of the company’s limestone quarries. And, with the new rig, each foot drilled is more productive. “Since switching to the larger drill steel, we’ve also increased the size of hole we use from 3.5 to 4 in.,” explains Ramey. “The larger holes mean that we can spread out the pattern of holes we drill for each round.”

Straighter Holes
In addition to raising productivity, the Pantera-Sandvik60 combination has also addressed the other major issue which motivated the company to change its drilling equipment — hole deviation. According to Ramey, “The hole deviation problems which we were experiencing with the T45 steel have improved by about a third since we switched to Sandvik60. I believe that the female coupling arrangement in the Sandvik60 steels has contributed a lot to this improvement in hole straightness.”

More Holes a Day
Cook, rig operator, says, “On the old rigs I was able to drill an average of 10 holes a day, whereas with the Pantera and the Sandvik60 steel, I’m averaging 16 a day.” Another feature of the new equipment which Cook likes a lot is the ease and speed of the automated decoupling system: “I’d say that the decoupling process is 50 percent faster on the Pantera compared to the previous rigs.”

According to Roger Ramey, superintendent of the Sylvatus Quarry, the new drill has reduced hole deviation by approximately 30 percent.

Tech Trends

Sophisticated Blasting Service

Full-service explosives suppliers provide expertise and technology to meet growing blasting challenges.

By Bob Drake

Full-service explosives suppliers can integrate blast design, hole drilling and logging, and explosives loading to optimize fragmentation and minimize vibration.

Blasting generally is considered the most efficient way to crush stone. But in today’s quarry operations — constrained by federal, state, and local regulations; security concerns; litigious trends; and public misconceptions — that efficiency is only achieved with a significant level of sophistication and care.
The blaster’s job is part art and part science, according to E.J. Burke, manager of stone and construction for Dyno Nobel. Blasters use a palette of explosives, initiation devices, analysis tools, engineering, public relations, and experience to simultaneously address issues such as safety, vibration, air blast, fragmentation, and muck pile shape. This must be accomplished in a production environment under sometimes variable geologic and weather conditions.
Consequently, aggregates managers increasingly are turning to full-service explosives suppliers to provide the level of expertise and sophisticated technology that can be difficult to maintain in-house. And correspondingly, as the explosives manufacturing business has consolidated and blasting has become more sophisticated, the few remaining “powder” suppliers have increased their focus on service. “It’s hard to differentiate [explosives suppliers] on the basis of the basic product and price,” says Burke. “We differentiate by people. Local relationships between the blaster and quarry people is important.”
The focus on full service is one of the predominant changes in the explosives industry over the last 10 years, according to John Capers, technical manager for Austin Powder Company. “These changes have enabled quarry operators to take advantage of cutting-edge technologies at the time of inception, using expert personnel from the explosives manufacturers who remain current in all blasting technologies,” says Capers. “The personnel are the highest trained explosives professionals the industry has ever had. They must remain current in all blasting related technologies as well as U.S. Department of Transportation; Bureau of Alcohol, Tobacco and Firearms; Mine Safety and Health Administration; Occupational Safety and Health Administration; Environmental Protection Agency; and state rules and regulations.”
Nevertheless, Burke says that some quarry companies don’t use the explosives suppliers’ expanded services, choosing to retain blasting as one of their core competencies. But, even in these cases, basic services are important.
“The proper explosives arriving at the quarry on time with properly trained personnel and equipment are the most fundamental and important things that a blasting service provider can offer to its customers,” says Capers. “The explosives industry must maintain specialized bulk equipment designed to fit all blasting applications, including vehicles designed to site manufacture explosives as needed or to blend various products.”
Powder, plus . . .
For quarry operations outsourcing blasting operations, however, explosives manufacturers offer a complete array of basic to high-tech services. Although blasting technology has become more sophisticated, “it really starts with drilling,” says Burke. “You need properly drilled holes and information from the holes in order to load [them] properly.”
Dyno Nobel and Austin Powder Company, as well as some other explosives suppliers, can provide complete service, including blast design, drilling, vibration monitoring, and blast documentation. Both companies can use blast-design software, laser face profiling, borehole deviation measurements, high-speed film and video, and fragmentation analysis to optimize drilling and blasting operations.
In addition, Dyno Nobel says that it provides complete documentation of blasting programs and helps with record keeping and analysis of blasting results and total costs. Austin Powder says that it provides electronic blast reports and developed software called QED, which is a virtual blasting program for forecasting fragmentation, damage, muckpile shape, and vibration levels. All of Austin Powder’s regional and corporate technical personnel have mining experience or mining degrees, which can add to quarry operators’ knowledge resources, according to Capers.
Both Capers and Burke expect explosives suppliers to continue to develop services and technologies in response to aggregate producers’ needs. In particular, Capers mentions needs related to community relations and environmental concerns, such as vibration and air blast, as quarries expand and urban development encroaches.
“New technologies, such as electronic detonators and chemically sensitized (lower density) blasting agents enable the industry to better influence these environmental results,” he says. Capers also predicts that aggregate producers in large metro areas will develop more operations as underground mines.
Burke expects greater demand for improved initiation systems and greater attention to regulatory matters. “Producers want safe operations and blasting that lowers overall production costs, even if it slightly increases blasting costs,” he says.

Electronic blast reports document every aspect of each shot and provide historical records for analysis and regulatory compliance. Source: Austin Powder.

Enhanced Security
With increased concerns about terrorism, quarry operators must take greater care in maintaining the security of blasting materials. This can make blasting services more attractive to producers who don’t want that liability.
“The explosives industry has, by nature of our product, always been security conscious,” says Austin Powder’s Capers. “Within one hour of the terrorist attack on 9/11, the member companies of The Institute of Makers of Explosives enacted additional measures to increase security.” He says it is not appropriate to describe the type of increased security currently in place.
Burke, of Dyno Nobel, confirms his company’s increased security at magazine sites and for transportation operations. “Company vehicles are in constant communication,” he says. “Nothing is stored on [the quarry] site.”
On Nov. 25, 2002, President Bush signed the Safe Explosives Act, which strengthens licensing and permitting requirements, according to the Bureau of Alcohol, Tobacco and Firearms (ATF). The new law requires thorough background checks on explosives users and federal permits for interstate and intrastate shipments. Check the ATF web site for more information (www.atf.treas.gov).

Bob Drake is editor for Aggregates Manager.