Greenprint Denver: Cleaning up the Platte
By Tillie Fong 
| August 12, 2009 | 7:01 AM
Reducing levels of E. coli bacteria in the South Platte River is one of Greenprint Denver's goals. (Photo by denvergov.org)
Greenprint Denver is halfway through its four-year plan to make Denver more sustainable. This is the first in a series looking at specific goals in the plan and the progress that has been made.
Going for a summertime swim in the South Platte River can be a dangerous proposition because of high concentrations of E. coli bacteria in the water. By 2011, though, Denver plans to get the river clean enough for people to cool off with a quick summer dip without putting themselves at risk of getting sick.
“We have been taking a proactive approach and started three to four years before we were mandated to do something about it,” said Darren Mollendor, water quality engineer for Denver Public Works.
High E. coli levels were found in 1998 in Segment 14 of the South Platte — the part that runs through Denver — and the Environmental Protection Agency put this stretch on its “impaired waters” list.
In 2007, Denver was ordered to come up with a plan to make the water safe enough to swim in, meaning reducing E. coli levels to 126 colony-forming units per milliliter.
“We meet that standard for Segment 14 for most of the year,” Mollendor said. “But during the summer months, we exceed that. In the middle of winter, we’re doing just great.”
Cleaning out the pipes
Under Greenprint Denver, an ambitious plan to make the city sustainable, officials in 2007 set out several goals to identify sources of E. coli in the South Platte and take measures to reduce or eliminate them. Many of the goals involve identifying contamination problems and maintaining Denver’s vast network of sewer and stormwater pipes.
E. coli can come from a variety of sources, including stormwater drainage, sewer cross-contamination, wildlife and pets.
“What we’ve done is to develop a plan to identify storm drainage basins with elevated levels of pollutants, and go through evaluating the underground sewer system and mitigate the impact,” Mollendor said.
Denver has 550 stormwater basins with drainage pipes feeding into the South Platte River, and one sanitary sewer basin that discharges into the Metropolitan Wastewater Treatment Plant.
In 2007, the city developed a geographic information system that locates where sewer lines go over or intercept stormwater pipes. Last year, the system was used to pinpoint problem areas. Eight stormwater basins have been identified for cleanup, with three targeted for completion this year and the remaining five by 2011.
“We have inspected those, and where we have potential of contamination, we have begun cleaning and restoring the pipes,” Mollendor said. “Wherever we find deteriorating pipes, we repair or place it on the list to replace it, or put in a liner to restore integrity.”
Two basins, containing 609,152 feet of sewer line and 398,219 feet of stormwater drains, have been cleaned, while a third basin is considered 80 percent done. That basin contains 849,158 feet of sewer pipe and 300,542 feet of stormwater lines.
Last year, the city spent $11 million to clean and repair sewer and stormwater pipes. This year’s expenses have not been tallied, but two new pieces of equipment were ordered and four field staffers were added to help with inspection and maintenance.
“Future budgets have been frozen,” Mollendor said. “We’re using the resources we have to focus on the more polluted basins.”
Mollendor said he doesn’t know how many sewer or stormwater lines eventually will have to be cleaned, repaired or replaced, but the city has 1,875 miles of sewer lines and 985 miles of stormwater pipes.
“Parts of the sanitary sewer system exceed 100 years in age,” he said. “Any problem with the South Platte River has developed in that time frame. It will take 10 to 20 years to remedy.”
Picking up after pets
This spring, a water quality program manager was hired to make sure that Greenprint Denver’s goals for water quality are being met. The city also has tried to address another source of E. coli: pet waste.
“People are not picking after their animals, and if they are, they’re not disposing the waste properly,” Mollendor said. “They would go and dump the waste in a storm outlet. We’ve identified areas where that happens.”
He said that many people think organic waste is biodegradable and won’t harm the environment.
“But if you have a large concentration — we’re talking about 30,000 to 40,000 dogs — the natural process can’t break down the waste, and it all washes into the river,” he said.
In 2007, Public Works mounted a “Keep it clean, from drain to stream” campaign, which ran on 9News’ Live Green program. Last year, the campaign was continued on radio.
This year, however, the focus is on street sweeping.
“Anything that is not picked up — leaves, grass clippings, sediment — goes into the storm sewer and the river,” Mollendor said. “If you were to take everything that is collected in street sweeping, and put it in Coors Field, it will fill it 8 to 9 feet deep.”
The city also is beefing up its effort to go after people who dump things illegally into storm sewers or the South Platte. Last year, 62 investigations into these violations led to 29 enforcement actions. This year, there have been 45 investigations, with an estimated 40 percent of those resulting in citations.
“We find a lot of after-the-fact dumping,” Mollendor said. “If we do find the culprits, we get restorative orders and we have to fix them (the problem). So we try to recover the costs in addition to the fines and fees.”
Despite Denver’s current budget woes, Mollendor said he is hopeful that the city will achieve its 2011 water quality goal.
“Denver is more progressive and more proactive than some folks in the surrounding community,” he said. “We have a citizenry that supports those kind of efforts, and we have the greenest mayor in the state.”
Darren Mollendor, e. coli, environment, epa, Greenprint Denver, pet waste, sewer, south platte river, stormwater, water quality
