Precision Mapping System for Water Runoff

Landscape Architect Who Has Designed a Precision Mapping System for Water Runoff Which Can Be Used in Storm Water Management

One recent morning, Matt Graham parked on Swan Way in Morningside and noted a small backyard that was unusually green. The lawn meets the alley at a trough in the pavement —rain diversion at its most rudimentary.

"Let's see how much rain drains to the [municipal] inlets here," he said, tapping his laptop to summon a map. He found the location and drew a box around it. Tap, tap. Click. The result: 478,000 gallons a year.

In a typical year, precipitation that overtakes combined water and sewer pipes sends 9 billion gallons of sewage into the region's waterways, said Jeanne Clark, spokeswoman for Alcosan (the Allegheny County Sanitary Authority).

Because of this, Alcosan and the 83 municipalities it serves are under consent agreements to comply with county health and state and federal clean water mandates by 2026. The costs of updating the systems range from $2 billion to $3 billion.

Ms. Clark said half the water Alcosan treats is rain or groundwater leaks. If rain is diverted from those pipes by "green infrastructure" —rain gardens, swales, water sculpture and underground systems —it can infiltrate into the ground like it's supposed to, preventing sewage overflows and sparing every Alcosan rate payer unnecessary treatment costs. The more traditional form of construction— underground storage tunnels and bigger collection pipes— is known as"gray" infrastructure.

With growing demand for green infrastructure as part of the big fix, Mr. Graham's stormwater data and mapping service, the GOAL Process, has broughtprecision to the task of compliance, showinghow soil composition, terrain, elevation and the built environment affect where raindrops go after they hit the ground.

It has shown that green infrastructure, indeed, has a place in the big fix — and it can pinpoint the optimal places.

Mr. Grahamidentified drainage routes to 40,000 inlets where combined water and sewer lines are still used. Dropping virtual raindrops, he asked the system to rank the inlets by gallons of flow.The result was startling and exciting in the potential for big-impact projects: nearly 12 percent of inlets took more than 50 percent of the flow.

If the region is looking at a $2 billion to $3 billion fix, Mr. Graham said, why wouldn't we install green infrastructure where it can divert the most gallons per dollar spent?

That question has already guided storm water diversion projects in high-yield sites from Etna to the East End's Project 15206 to the South Side's 21st Street. Mr. Graham has becomea go-to resource on300 site designs and hashelped municipalities update their maps.

A landscape architect with engineering experience, Mr. Graham developed geographic information software in the 1990s that secured him a lucrative contract with Sprint. In 1996, he and his longtime friend Richard Thorne founded Landbase Systems, for which Mr. Thorne's expertise in high-speed cloud based solutions has made "all things possible" in Mr. Graham's pursuit of green solutions for storm water.

He designed the GOAL Process to show millions of calculations graphically. Itcan trace surface water above an inlet. Mr. Graham can click on"surface trace" to see the area of the flow. He can prompt the data to show him where water is flowing. Color coding shows variations in elevation.The computer does all the work except what the eye needs to see, he said during a drive around the city,"then you have to go out and look." Go out and look — that's what GOAL stands for.

He uses the system to show him what is happening in real time. During one particularly heavy rain, he checked it to see where water was gushing. He drove to 48th and Harrison Streets in Lawrenceville, where rain was swelling along one portion of 48th.

"I calculated that 1 million gallons a year could be captured there. This is low hanging fruit," he said, noting the number of large warehouses whose downspouts could be redirected. "The best solution would be infiltration through subsurface storage on the edges of the road.

"Every time you have to dig into the streets," he said,"there should be a plan for how green infrastructure could be installed."

On the recent drive around the city, he noted sites where tens of millions of gallons could be diverted each year: the Port Authority parking lot on Washington Boulevard in Larimer, the Shop 'n Save parking lot on Butler Street in Lawrenceville, Bartlett Street in Squirrel Hill and several streets in Homewood.

One of those streets, Wheeler Street, is a cascade of rain that misses inlets all the way from Penn Hills, he said. "Interception points in a stepped-down design could help Nine Mile Run and reduce flow to Negley Run."

Brenda Smith, executive director of the Nine Mile Run Watershed Association, has been working with Mr. Graham to identify opportunities to reduce run-off into into that stream, whose watershed is 6.5 square miles through Squirrel Hill, Point Breeze, Homewood, Wilkinsburg, Edgewood and Swissvale.

One site of great potential is acombined sewer overflow near the Wilkinsburg busway.

"It empties into an underground tributary of Nine Mile Run," Ms. Smith said. "Twenty-five million gallons of storm and sewage overflow into Nine Mile Run every year" from there.

In Etna, green infrastructure at 23 sites will keep 16.1 million gallons out of the borough's and Alcosan's systems each year, said borough manager Mary Ellen Ramage.For a one-time cost of $6.1 million, Etna's green infrastructure — including a parking lot rain garden to a collection system under sidewalk grates — will sequester and naturally infiltrate close to 20 percent of the rain Etna would otherwise contribute to the system.

John Schombert, executive director of Three Rivers Wet Weather, said 20percent is the best expectation of green infrastructure's role in the regional fix. "It would be difficult to make it more than that because of development and private property" constraints, he said.

"I think we can do more than that," said Mr. Graham, noting that most run-off is on city streets and most opportunities are in public rights of way. "In places that are flat, I'd agree with 20 percent, but in Pittsburgh we have a bigger opportunity because of the geography. I think it could be 40 to 50 percent."

Notably, the GOAL Process has been used in Project 15206, named for the ZIP code in Highland Park and Morningside. It is a multisite effort to intercept storm waterinHeth's and Negley Runs with a variety of green infrastructure, from bioswales to babbling brooks to water amenities people could play in.

Storm water has been the source of chronic flooding on nearby Washington Boulevard, where four people died in a storm surge in August 2011.Every year, between 700 and 800 million gallons of storm water in the Negley Run watershed end up in one overflow near the Highland Park Bridge.

Ms. Clark at Alcosan said that is the single largest overflow site in the service area.

The Penn State Center is managing Project 15206, an initiative of state Sen. Jim Ferlo, D-Highland Park.It is in the design phase, with commitments from the city's Department of Public Works to build the Negley Run projects, said Lisa Vavro, sustainable environments manager for the Penn State Center.

"I don't think we could do Project 15206 without Matt's analysis," she said. "Itis so detailed and more out of the box than you would find in normal engineering scenarios."

Heth's Run lies in a gorge below Morningside. Chislett Street, a few blocks from Swan Way, lies along the rim.

AtChislett and Vetter, Mr. Graham stood beside an intake drain with his laptop. He asked the same question he had asked on Swan Way: How many gallons drain to nearby intakes? Tap tap tap. Box. Click: 730,000 a year. A perfect spot for a storage system under the sidewalk with a slow-release feature that would link to the Heth's Run project.

"The biggest opportunities are the natural infrastructure of parks," he said later, stopping in Lawrenceville, along the 40th Street side of Arsenal Park. "When 40th Street sends water down in sheets, curb inserts could intercept it and filter pollutants out then release the water slowly into the park."

As planning begins on a renovation of the park, Mr. Graham is consulting on its green infrastructure. He said it could become "a spectacular example of a water amenity" instead of water down the drain.

In Squirrel Hill, Mr. Graham turned onto Bartlett Street. "Water blows right by inlets in this street and goes into inlets at the entrance to Schenley Park.Bymy calculations, 14 million gallons could be captured here and slow-released into the park.

"If you take water into a system that slows it, filters it and infiltrates it, any natural stream can handle that," Mr. Graham said. Instead of paying Alcosan to treat it, he said, microbes and wetland creatures will do it for free. "That'sa double win."

Source: Pittsburgh Post Gazette

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Taxonomy

• Leakage
• Groundwater Recharge
• Groundwater Mapping