Every drop for green cause

Paul Mankiewicz, a biologist, botanist and erstwhile philosopher, has a vision for New York City.

He calls it “zero discharge'': Not a drop of water should escape from the city without first making something grow.

Rainwater should be caught and used to cultivate greenery. “Grey water'' from showers, baths and sinks should irrigate rooftop gardens.

Trees dotting streets are good but a belt of grasses and shrubs lining roadways would better catch and utilise runoff.

Restored wetlands around the city would filter any water that escapes. All water entering the city should pass through a natural system on its way out.

“What you have to do is bring the land to life,'' he says. “Our footprint is not an abode for life. It's the opposite; it's sterile.''

Mankiewicz, executive director of the Gaia Institute in New York and treasurer of the city's Soil and Water Conservation District, has designed ecosystems for 30 years.

He had a hand in the city's very first “green streets'', patches of greenery sprouting up alongside roadways in recent years and the Bronx's first green roof.

His guiding principle: Living systems can achieve naturally what humans endeavour to do artificially.

Soil microbes and plant roots can digest the carbon-based molecules that collect in the average city gutter.

“You have to rethink the permeable and impermeable,'' he says.

Standing beside a 300-square-foot Bronx green street he helped design, Mankiewicz expounds on the value of living soil.

Normally, the city has to treat runoff before releasing it into waterways. But this patch of green could absorb much of the 50,000 gallons of runoff generated in the city in a year.

Multiply that by some 2,000 green streets now in existence and the result is some 100 million gallons of water not going down storm grates.

Over the years, Mankiewicz has emphasised the critical role of dirt, says Robert Alpern, an adviser in the city's Department of Environmental Protection under former mayor David Dinkins: “His major contribution has been to sensitise the bureaucracy to the potential of soils as a filtration and infiltration medium for storm water.''

Shed weight, hold water

On St Simon Stock Elementary School's rooftop garden, Mankiewicz explains the greatest hurdle to greening the city's 35 square miles of rooftops: The average cubic foot of dirt weighs between 45 and 55 kilograms, around three times the load for which most roofs are engineered.

So he designed his own soil, substituting ground polystyrene (Styrofoam) for much heavier sand and clay.

The result, patented as GaiaSoil, weighs about 5 kg per cubic foot and can hold twice its weight in water. The next problem: New York gets about 102 centimetres of rain yearly but it doesn't come evenly.

A recent dry spell has left some of the Little Blue Stems, one of perhaps 25 native species atop St Simon's roof, looking forlorn.

Mankiewicz grew up in Bloomfield, New Jersey. When he was young, farmers in Bloomfield grew vegetables to sell in New York City. But urban sprawl eventually did away with the fields.

“All the areas I grew up with that were beautiful were paved over,'' he says.

He earned a BA in philosophy from the New School for Social Research and a PhD in biology from City University of New York, among other degrees.

In the 1980s, he spent lots of time at St John the Divine, an Episcopal cathedral in Morningside Heights and a hotbed of environmental thinking.

James Parks Morton, sometimes called “the green dean'', presided over and encouraged the religious-environmentalist ferment for 25 years, ending in 1997.

He recalls one project in particular: Inside a bay of the soaring Gothic cathedral Mankiewicz constructed a living model of the Hudson River ecosystem: Several 20-foot-long tanks filled with fish, “various green stuff'' and blue crabs.

In the 1980s, Mankiewicz itched to apply his ideas on ecosystem design to the real world. “People were saying, ‘interesting idea', but no one was doing anything,'' he says.

So in 1995, he incorporated the Gaia Institute, a non-profit. “Nothing was going to change, otherwise,'' he says.

It was an unusual move, says Dominick Basile, Mankiewicz's PhD adviser at Lehman College in the Bronx. Most biologists choose the reliable paycheque of research or academia.

But Mankiewicz and his wife, Julie, chose to “spread the gospel'' of biology.

Closer to ‘zero discharge'

Says Mankiewicz: “If you want quick money, never get into the green-roof business.'' For 25 years, the overriding problem was a lack of interest from on high.

City officials favoured a hard engineering approach — chemicals and machinery — to solve issues such as storm water runoff. Now that is changing. “People are just [now] getting it,'' he says.

The city now has 2,300 green streets, a programme begun under mayor Rudolph Giuliani in the 1990s. Mayor Michael Bloomberg has pledged to surpass 3,000 by 2017.

MillionTreesNYC aims to plant 1 million more trees throughout the city in the coming years. (The present tree census: 592,130.) It is all inching the city closer to Mankiewicz's “zero discharge'' dream.

“It would change the local climate,'' he says, “and that would be magnificent.''