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Denton's solid waste audit finds weaknesses

An audit of Denton’s Solid Waste Department has found weaknesses in its management, particularly in handling new projects, equipment use and staffing.

Dallas-based firm Weaver conducted the audit and is expected to deliver its report to city leaders this week. The report is one of two highly anticipated reviews scheduled for the Public Utilities Board agenda Monday and the City Council agenda Tuesday. The other report follows a review of air emissions expected from the Denton Energy Center, the city’s controversial new natural gas-fired power plant under construction near the airport.

The new solid waste management team is scheduled to follow Weaver’s report with its own report. They have already taken some corrective steps in response to the audit and are expected to explain those changes to city leaders.

To prepare the audit, Weaver interviewed employees in solid waste and reviewed procedures for key business activities at the landfill. In addition to burying garbage at the dump, Denton diverts tons of waste through innovative recycling and reuse programs. Some of the gases produced by decaying waste are used to make electricity.

An electric generator that burns methane gas to make electricity at ECO-W.E.R.C.S. Resource Recovery Park.  This generator can help power about 1,400 houses. DRC
An electric generator that burns methane gas to make electricity at ECO-W.E.R.C.S. Resource Recovery Park. This generator can help power about 1,400 houses. 
DRC

Weaver outlined 10 significant weaknesses that make it difficult for the department to predict and manage costs, which could ultimately affect ratepayers. About half of the identified weaknesses had to do with the department’s ability to identify what constituted a project, and therefore how to develop and evaluate it. Weaver also outlined other weaknesses that weren’t as significant, but needed to be addressed.

A management reply to the Weaver report showed the department taking corrective steps to address all the weaknesses, regardless of priority.

The report does not discuss two major steps the department has already taken. In September, the City Council canceled a program that would have mined the landfill for recyclable materials after the new management team found it wouldn't be cost-effective. 

The City Council also agreed to stop buying natural gas-fueled garbage trucks after learning that the city likely lost $1 million or more on the gamble that the fuel would cost less than diesel. 

Air permit review

Activists and council members questioned whether the emissions estimates for Denton’s new power plant are correct, especially when compared to the Red Gate Power Plant near Edinburg in South Texas. 

A dozen natural gas-fired engines, similar to the engines that power cruise ships, make up the heart and soul of both the Red Gate plant and the Denton Energy Center. Denton’s power plant is not expected to run all the time, unlike Red Gate, which is expected to run continuously.

In their report, engineers with Black & Veatch said they found small differences in the rate of emissions at Red Gate when compared to anticipated emissions at the Denton Energy Center.

Some of the differences could be explained by the different way Denton’s power plant would scrub emissions compared to Red Gate. The “selective catalytic reduction,” which operates akin to a catalytic converter on a motor vehicle, would be tuned to trade fewer ozone-producing compounds for those that would emit more particulate matter instead.

However, the engineers said they couldn’t explain in the report how the devices would work because the information is proprietary to Wärtsilä, the engine manufacturer.

Denton’s contract with Wärtsilä requires the company to keep tuning the engines and the emissions-reduction devices until emissions levels reach the level required by the state for operation.

The Public Utilities Board meeting begins at 9 a.m. Monday. The City Council meeting begins at noon Tuesday. Both meetings will be at City Hall, 215 E. McKinney St., and live-streamed on the city’s website, www.cityofdenton.com

PEGGY HEINKEL-WOLFE can be reached at 940-566-6881.