Lightening The Load

Lancaster is helping the Chesapeake Bay by using green infrastructure to efficiently reduce the load on its combined sewer system and eliminate CSOs.
Lightening The Load
From Left: Capital Improvement Program Manager Matthew Metzler, Mayor Rick Gray, Director of Public Works Charlotte Katzenmoyer, and Environmental Planner Karl Graybill pose in front of Lancaster’s City Hall.

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Lancaster, Pa., sits on the Conestoga River in the southeast corner of the state, some 60 miles west of Philadelphia. The Conestoga is a tributary of the Susquehanna, the largest river emptying into Chesapeake Bay. Lancaster contributes about 1 billion gallons annually to this watershed, too much of that fouled by combined sewer system overflows. The cost to store and treat this water conventionally would be prohibitive. Green infrastructure provided the better solution.

Founded and platted in the 1730s, and incorporated in 1818, Lancaster is rich in history (see sidebar). Unfortunately, that history includes an old combined sewer system with antiquated pipes and pump stations. Lancaster is one of about 770 combined systems still operating around the country.

“That old pipe and other infrastructure was causing problems,” says Charlotte Katzenmoyer, director of Public Works. “We didn’t have a consent decree from the EPA, but we did have an administrative order, so in 2011 we got started with our greening plan.”

That plan included a partnership with CH2M HILL in 2011, and the nongovernmental organization LIVE Green, now merged with the Lancaster County Conservancy. CH2M HILL focused on developing the best GI plan possible. LIVE Green handles the public outreach and educational programs, and maintains the City of Lancaster website.

The city had upgraded to an advanced wastewater treatment plant in 2005, using the OASES activated sludge process (Kruger USA) with enhanced biological nutrient reduction. Its capacity is 32 mgd. They also upgraded their eight pumping stations. The system works as designed 85 percent of the time, sending the combined waste load to their plant. But despite spending $18 million on gray infrastructure, the system was still being taxed by heavy rain events.

Green vs. gray

The alternative to GI would have been extensive upgrades to Lancaster’s gray infrastructure. “The choice was really a no-brainer,” Katzenmoyer recalls. “When we ran the numbers, a gray infrastructure solution would have cost us $300 million, or about 30 cents per gallon. Using green infrastructure, those numbers dropped to $140 million and 16 cents per gallon.”

Katzenmoyer, who was trained as a traditional engineer, was at first skeptical that green infrastructure alone could do what was needed. “But when I looked at the plan and saw that we needed to mitigate only about 50 percent of our impervious area, I was convinced it could be done,” she says. “And our economic projections are confirmed by the data already in. We’re actually lower than 16 cents per gallon on most of our demonstration projects.”

Karl Graybill, environmental planner for Lancaster, notes “To do this right, we’ll need to focus on how to properly maintain all these widely decentralized projects. If they aren’t functioning at design capacity, we’re right back to square one.”

Much of the cost of GI will be supported by user fees that are based on the amount of impervious surface on each property. The fees were approved by the city council in February. The remaining costs will come from state and federal grant programs, and several NGOs such as LIVE Green.

Lancaster hasn’t totally ruled out gray infrastructure upgrades. They are closely monitoring the system to identify where, if at all, it would make sense to split the CSS. All 7.4 square miles of Lancaster is essentially “built out,” with a final subdivision just now going in.

“The key issue is that there are a few places in the system where it would be easy to separate the flows, and we’re looking at that. But when you compare the maintenance costs of GI to the averted cost of upgrades and SSOs, that’s the main reason we’re pushing GI,” Katzenmoyer says.

The plan so far

Lancaster was one of the first cities in Pennsylvania to adopt a green approach to solving runoff and CSO issues, so they have been paying attention to what works well in other communities. Now only three years into their plan, they intend to continue expanding GI over the next 22 years.

The list of active demonstration projects is impressive. Deployed to date:

  • Downspout disconnections
  • Cisterns and rain barrels
  • Bioretention rain gardens
  • Vegetated roofs (15 and counting, highest per capita in the country)
  • Stormwater planter boxes
  • Pervious pavement instal lation
  • Green streets and green alleys (with bicycle lanes where space permits)
  • Vegetated swales
  • Tree trenches
  • Vegetated curb extensions
  • Tree planting and replacement (understory and large shade)
  • Soil infiltration testing

These demonstration projects are functioning as expected, and generating a lot of public interest. “When we go to a home or business to advise on GI, we bring along all the ‘how to’ brochures, which are also available on our website,” says Fritz Schroeder, director of Urban Greening for LIVE Green. “We want to make this easy for the property owners.”

Graybill adds, “We have to consider the different needs of residential, public and commercial properties, and make sure the GI solution fits the problem.”

By the time the full project is complete, Lancaster projects they’ll be removing a billion gallons per year from their treatment system. They’ve already cut that load by 15 million gallons.

With 3,539 acres in their jurisdiction, Lancaster has 969 zoned as residential. This venue is where effective GI implementation will provide the greatest payback. “We don’t have enough public land in the city to do this all on our own,” says Katzenmoyer. “Half the relief we need will come from private property owners, so we’ve got to provide incentives for them to do their part, like rates based on impervious area, and grants to actually build their own GI on site. We intend to set aside close to $70 million for those grants over the next 22 years.”

That money will come directly from their stormwater management fee, which is based on the total impervious area on each property as assessed by aerial photos in their GIS. That charge is $7.50 per 1,000 square feet of impervious area per quarter. So the economics are basically a zero-sum game, with the city redistributing most of those dollars as needed to advance their residential and commercial GI programs.

“That only covers a portion of the whole GI plan,” says Schroeder. “At this point, the program is still in its early stages, running on state and federal grants. But that’s been enough to let us fully develop our public spaces wherever we want.”

Public outreach

Lancaster has built an outstanding website – now being maintained by Schroeder and LIVE Green – to help them reach their GI goals. The entire 240-page GI plan prepared by CH2M HILL is there, along with photos, plans and instructions for residential, commercial and public GI projects.

The city also provides continuing bus tours showcasing GI projects in Brandon and Crystal parks, as well as Buchanan Dog Park and St. Anne Peace Garden. In the future, as more residential projects are completed, they’ll expand that tour to include examples of vegetated roofs, rain gardens and other projects done by property owners.

“We’re already doing some of that,” says Schroeder. “We’ll get a group of adults from a local club, or students, and take them to Crystal Park, one of our model projects. From that location we can easily show them a residential green roof or rain garden. It’s part of a ‘walking tour’ where they can see what other property owners have done.”

Of interest is the impact of their first “green street” project, where a major intersection with originally impervious paving was totally redone according to GI best practices. “It looks so nice now that people slow down to enjoy the view,” Katzenmoyer says. “We measured a 5 mph decrease in average traffic speed through that intersection.”

And of course, outreach is extended to area schools in the form of tours, talks and workshops. Materials for educators are also available on the Lancaster website.

Where to from here?

“It’s not just about Lancaster and Chesapeake Bay, or the fact that we have a combined system.” Katzenmoyer cautions. “As more homes get built, and the amount of impervious surface increases, we’re seeing a national trend in runoff problems. We need to stop and reverse that process if we’re going to protect our waterways for future generations. That’s what we’re trying to do here in Lancaster.

“And by rolling our GI projects into other capital development, we’re reducing our up-front costs. For example, if we’re putting in ADA ramps at an intersection we’ll go ahead and do the green curb extension at the same time. And just recently, we added an annex to City Hall, so we put a green roof on it. Also, during a routine park renovation, we rebuilt a basketball court using permeable surfacing, and an underlying infiltration bed to accept stormwater from the surrounding streets.”

Public support is a large part of their success. Current Mayor Rick Gray is a huge advocate of GI. During the last election, his opponent was opposed to using GI, and there was an outpouring of citizen comments on the Lancaster newspaper’s website in favor of candidate Gray and GI.

“People notice GI,” Schroeder says. “They see the difference it’s already making in aesthetics, air quality and reduced CSOs. We’re kind of ahead of the curve here in Lancaster, but we’re watching closely what works for other cities trying this approach, many on the west coast where GI originally took off. We’re all learning from each other.”

Graybill says it’s all a balancing act. “We have to look at the overall costs, environmental impact and citizen acceptance, which so far has been encouraging. Then we need to choose the right projects at the right time and place, as we’ve done with many of our peripheral capital development projects.”

The city is in a good place now and is on track for expanding its GI over the next two decades, Katzenmoyer says. “We’re seeing the results we expected, and we’re optimistic about how far GI can take us. In terms of sustainability, GI is right for Lancaster.”

More Information

BOMAG Americas, Inc. - 800/782-6624 - www.bomag.com/us

CH2M HILL - 888/242-6445 - www.ch2m.com

Godwin, a Xylem brand - 800/247-8674 - www.godwinpumps.com

Ingersoll Rand - 704/655-4000 - www.ingersollrandproducts.com

John Deere - 800/503-3373 - www.johndeere.com

Kruger USA - 919/677-8310 - www.krugerusa.com

Vactor Manufacturing - 800/627-3171 - www.vactor.com



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