After hearing long analysis of the Marana Regional Landfill's potential impacts upon groundwater, surface water, traffic and the airport, Town Councilman Jon Post had to step back and wonder about scale.
"One of the issues I'm having a hard time getting around," is "a 500-acre site that's 200 feet of trash," Post told Michael Racy, the consultant for DKL Holdings. "I just can't figure it out. What are you going to put in there?"
"What you want for the region is a single, large facility," Racy said. Modern landfills are "only viably developed on a large basis." Smaller landfills are "not economically viable." This facility would have "an extremely long life for waste from this entire region," Racy continued. "You want to concentrate into single large facilities to serve all of northern Pima and southern Pinal counties."
As a comparative, the Cactus Waste Landfill in Pinal County covers 550 acres, and would be 270 feet tall when finished, Racy said.
"This is the size these modern facilities are designed to," Racy said. "That's the world we live in today. It's just too expensive to build at 100 or even 200 acres."
State trust land is on three sides of the Marana Regional Landfill site, a 430-acre disposal area within 590 acres one mile north of Avra Valley Road, and ½-mile south of Silverbell Road. There is farmland to the south.
A "green buffer" area of 200 feet would surround the landfill on its north, south and west property lines. That buffer increases to 400 feet on the northeast side, which is approximately a half-mile from the Silverbell West residential development.
It would be "a privately owned and run operation," said Kevin Kish, general manager of development services for the Town of Marana, "not quasi-public, not Town of Marana."
The landfill would have eight cells, each of eight to 10 acres, the first to be opened on the lower southwest corner of the project. At its highest point, the landfill would reach 195 feet near its middle.
"If this continues to move forward, there's still a lot of steps," Kish told the council. Various plans and agreements are required, along with "many state and federal permitting processes they'd need to go through." Beyond various analyses, developers must create a "financial assurance mechanism" for eventual closure of the facility. It would also cover any remedial clean-up action.
"We want to emphasize that this is the very beginning of a very long process," Racy said. "Questions, tonight, are part of the permitting process that we can't start until it goes through the zoning process. Issues will be addressed."
A development plan is being written. The council must still consider a zoning change for the project. DKL is planning an open house next Thursday, July 8, from 10 a.m. to 6 p.m. in the second floor conference center of the Marana Municipal Complex.
A proposed landfill opening date is 2013.
Groundwater would be 100 feet below facility's bottom
Groundwater beneath the proposed Marana Regional Landfill site is not likely to come within 100 feet of the landfill's lined bottom, according to a consultant who addressed the Marana Town Council last week.
At its deepest, the 430-acre landfill would reach 70 feet below the surface, Mark Cross of Montgomery and Associates told the council. Most of the landfill base would be 40 feet deep.
"The natural ceiling" of the underlying aquifer "would normally be, in the absence of recharge, approximately 170 feet below the land surface," Cross said, or 100 feet below the landfill's deepest point. "It's unlikely it would be shallow enough to rise above the base of the landfill. It certainly could come closer, to within several 10s of feet of the base of the landfill, especially if recharge increases. If owners begin to pull stored water, no."
Opponents have repeatedly claimed the landfill would sit atop one of the only rising aquifers in the Tucson Basin. Cross showed the council historical groundwater levels that have risen "in response to recharge."
Beginning about 1940, with pumping of the aquifer for agricultural use, groundwater levels north of the site declined up to 150 feet in some areas by the mid-1970s. Groundwater stabilized in the late 1970s and early 1980s, "probably due to a decrease in agricultural pumping," Cross said. Then, with Central Arizona Project recharge projects coming on line, water levels have risen in the 2000s, including an average increase of seven feet a year between 2000 and 2005. They remain at or near the 1940 baseline.
The same is true in a review of historic groundwater levels south of the landfill site, which is two miles south of the Santa Cruz River, and four to five miles west of Central Arizona Project recharge projects.
"What do you estimate the static water level will be?" Mayor Ed Honea asked.
"The brief answer is that rates of water level rise currently range as much as seven feet per year," Cross said. "Rates of rise will decrease with time, just naturally, if recharge rates remain the same. Increasingly, there will be pressure to recover stored water," and that will influence water levels.
"It is possible for water levels to get quite close to the bottom of the landfill, especially if recharge increases," Cross said. "However," given static recharge volumes, "water levels will be shallower than they are today."
Factors controlling the potential for groundwater pollution include landfill design and construction, the nature of deposited waste, precipitation, hydrogeologic conditions and depth to groundwater, and the direction and rate of groundwater movement, Cross said. Groundwater pollution can be avoided through design, construction, monitoring and corrective actions. The landfill would be lined, and equipped with a leachate collection system.
"We don't have a lot of liquids sitting in our landfills," said Michael Racy, representing developer DKL Holdings. The area has potential evaporation of 70 inches of water per year, and an average of 12 inches of rainfall. "Whatever rain we get gets evaporated back out."
At the landfill site, groundwater is moving west to northwest at a rate of 100 feet per year. There are domestic supply drinking water wells two miles west of the site. The "time frame down gradient" is about 50 years from the landfill site, Cross said.
Any water quality "effects would remain localized," Cross said. There is not "a guarantee there would never be a leak. If it was, it would likely be small," with monitoring triggering corrective actions.
The Tangerine Landfill is lined, Cross said. "There is no evidence of any effect on groundwater from the Tangerine Landfill," he concluded.
Construction would keep out Brawley flows
Construction around the Marana Regional Landfill would protect it from high water along the Brawley Wash, an engineering consultant told the Marana Town Council last week.
"With construction of drainage improvements around the perimeter, we believe the facility could comply with the Town of Marana floodplain ordinance," said Clint Glass, of the firm CMG Drainage Engineering.
There is an estimated 100-year discharge of 35,000 cubic feet per second at the confluence of the east and west branches of Brawley Wash, which is immediately north of the landfill site. Because the terrain is flatter, water is dispersed in a "more spread-out sheet flow," as compared to a more compact river flow such as the Rillito River, with steeper elevations and higher water velocities, Glass said.
Consultants review landfill effects upon traffic, airport
Findings of a traffic study done to analyze potential impacts of the Marana Regional Landfill are "reasonable," a consultant hired by the Town of Marana told the town council last week.
"What I can't say whether it's right or wrong is the trip generation," said Alejandro Angel, of Psomas and Associates.
Psomas was asked to examine the study "to decide if we concurred with the findings." The commercial landfill, proposed for land off Avra Valley Road, would generate an estimated 310 vehicles per day, making 620 trips in and out. Among them are 60 garbage trucks and 40 tractor/trailer transfer vehicles. That would mean a 15 percent of traffic on Avra Valley Road.
"That's significant," Angel said, "yet the capacity is 15,000 vehicles per day. Current traffic is 4,000 vehicles per day."
Avra Valley Road would be widened to four lanes by 2030, according to the Regional Transportation Plan. Even with a 25 percent increase in traffic through 2030, Avra Valley Road has "sufficient capacity" to handle the load, Angel said.
The existing pavement on Avra Valley Road is "poor and failing," Angel said. A bridge over East Brawley Wash is in need of evaluation. The developer would add turn lanes at the sole landfill entrance on Avra Valley Road.
Jim Harris of Coffman and Associates, the town's consultant on Marana Regional Airport for a number of years, said the Federal Aviation Administration "wants to be assured the landfill as an attractant to wildlife would not pose a significant impact to the airport."
The agency would evaluate the landfill's proposed highest point, 195 feet above the current surface, "to make sure it does not pose a hazard to aircraft taking off from and landing at" the airport, Harris said.