Lewis and Clark County is getting ready to start using a major new piece of infrastructure — a giant hole in the ground.
It’s a fresh, empty landfill cell, also known as Phase 3 in the county landfill, measuring 8.9 acres and about 40 to 50 feet deep. The landfill, on Deal Lane, is tucked unobtrusively between rolling hills in the Helena valley.
Late last week, county Solid Waste Manager Sherrel Rhys said the state Department of Environment Quality told her it was giving final approval for use of the cell, and it could start receiving garbage as early as this week.
It’s just a small part of the 80-acre landfill, which has a six-phase master plan. Originally envisioned with a 50-year life, Rhys said it’s now expected to last 75 more years thanks to improved methods of getting more and more waste into each cubic yard of space.
In the short run, the new cell will improve operations, letting the landfill operators save an area close to its entrance for wet days, so trucks bearing waste won’t have to travel so far and create more mud and ruts. The same 120-foot-thick formation of bentonite clay that provides an impermeable seal under the landfill is also difficult to drive on.
On top of the clay is a specialized plastic liner, topped by a fabric liner, and then a gravel layer with pipes to extract moisture and all the substances dissolved within and convey it to a pond for evaporation. So, no water that touches garbage should ever enter the groundwater or leave the facility. When the cell is full, the whole thing may be capped with more clay, entombing the waste, Rhys said.
It’s been in the works for some seven years.
“Once you start one cell then you’re already planning for the next,” Rhys said.
The landfill is the final destination for most solid waste in the county that is not recycled. Every day, as many as a dozen trucks haul garbage from the Helena Solid Waste Transfer Station. It’s packed down with heavy equipment, and every night the fresh waste is covered in fabric to protect it from the elements and animals.
That’s an improvement over the previous technique of covering it with 6 inches of dirt every night, and a significant reason the land fill is expected to last longer than originally planned.
“That adds up to a significant saving in landfill space,” Rhys said.
The construction of the liner and leaching system cost about $1.1 million, she said. Landfill staff excavated some 400,000 cubic yards of dirt at a fraction of the cost outside contractors offered, saving the county $500,000, she noted.
The landfill is also the site for some recycling efforts. It’s where the mobile glass pulverizer belonging to Headwaters Cooperative Recycling is located. The pulverizer grinds glass for various uses. Some of the pulverized glass is stored at the landfill. The site also hosts a major composting operation for plant waste materials.
“Instead of putting it in the ground and burying it, we’ve put it into a product we can use here locally,” Rhys said. And it’s cheaper to compost than it is to put it in the landfill.
A contractor uses the area to bale up tires received from the city and tire shops, which pay for the tires to be removed. And that’s fine with the landfill, because tires have a way of working their way to the top of garbage heaps and breaking through the caps seals, Rhys said.
Reporter Sanjay Talwani: 447-4086 or firstname.lastname@example.org