One of the biggest challenges facing those charged with regulating future development in Sammamish is the need to control what happens to rainfall after it falls on developed areas.
The basic situation is this: When it rains on undeveloped, forested areas, most of the water is absorbed into the soil and by flora. The excess is filtered through the soil, running into underground aquifers and streams.
This process is one that, perfected over the millennia, allows watersheds and systems downstream to cope with flows and make the best use of the moisture.
That system is broken when land in its natural state is covered in concrete and other impervious surfaces.
The rain is not able to be absorbed into the earth’s natural filters but instead falls on hard, artificial surfaces and flows in concentrated patterns at great volumes, often carrying with it pollutants such as oil from roadways and parking lots.
This impacts not only nearby lakes and streams but also the central watersheds, such as Lake Sammamish, the destination for the cumulative runoff of many hundreds of square acres of developed sites.
As the importance of better managing stormwater runoff seeps its way into legislation, cities like Sammamish are being asked to ensure new development takes steps to protect nearby streams and watersheds.
The Sammamish Planning Commission is currently waistdeep in a tide of new stormwater regulations and technology, as they consider how to plan a Town Center that will not become an environmental disaster.
In the past, at least one commissioner has raised serious doubts that the Town Center development would be able to mitigate the stormwater issues it would create, and many of the commissioners have advocated for Low Impact Design (LID) techniques to be a design standard, compulsory, rather than just encouraged in developers’ plans.
Erin Nelson of environmental sciences and planning consultant Parametrix told the planning commission last week that without significant LID efforts, an area equivalent to 11 percent of the Town Center would need to be provided as rainwater detention ponds, usually built underground, at great expense to developers.
Nelson said the use of bioretention techniques, such as green roofs and rain gardens, and widespread use of pervious paving, would reduce that figure to 7 percent.
Tanks – a good solution
The city’s efforts to better manage stormwater received an enormous boost with the news that outgoing Washington Department of Ecology Director Jay Manning had finally resolved what had been a bone of contention between water suppliers and ecologists, officially allowing the collection of rainwater in tanks for reuse.
The legislation signed by Manning, who is now the chief of staff for Gov. Chris Gregoire, said that a “water right” would no longer be required for the on-site storage and use of rooftop or guzzler collected rainwater. A guzzler collects water to feed animals and birds.
It was this protection of water rights, whereby landowners and government agencies effectively own the water in streams, rivers and creeks, that had prevented the harvesting of rain water. Catching rainwater and using it was seen to be essentially stealing a resource which belonged to someone else.
Nelson recommended to the commission, given the new legislation, that rainwater harvesting now become a significant part of their stormwater plan for the Town Center, particularly in the form of collection tanks on building roofs.
“This represents the single best reduction in (runoff) volume you can get,” she said. “Roofs represent a significant part of the urban area – up to 50 percent. Collecting waters in tanks really takes the pressure off freshwater resources.”
No input from water district
But as the city considers what could be the most significant alteration of the water rights scene on the Plateau, the group with arguably the biggest stake, the Sammamish Plateau Water and Sewer District, has been largely absent from discussions.
Planning Commissioner Scott Hamilton said he was “very disappointed, that at no time, when the original LID ordinance was being discussed, and when LID in the Town Center was being discussed, did anyone from the district show up.”
The Reporter contacted the water district for a comment, but did not receive a reply before going to print on Wednesday evening.
Water and Sewer District General Manager Ron Little did return The Reporter’s call on Thursday morning, saying that the issue of water rights and water usage was of great interest to his organization, which he said is supportive of water conservation.
Hamilton said that a representative from the North East Sammamish Sewer and Water District did offer testimony during LID ordinance discussion between 2005 and 2007, speaking in favor of LID techniques.
In a slide presentation to the commission, Nelson demonstrated that with comprehensive harvesting of rainwater in the Town Center, the percentage of land needed to be provided as rainwater detention ponds would be reduced to 4 percent.
City of Sammamish Senior Stormwater Program Engineer Eric LaFrance said he envisioned that apartment blocks and other multi-dwelling buildings would make good use of rainwater tanks.
“That’s where I see most of the usage,” he said. “On a big, flat roof you can collect a lot of water.”
LaFrance said that rainwater collected in tanks could be used for low pressure uses like toilets and irrigation, grey water uses. He said that allowing tanks would go a long way to helping the planning commission achieve their stormwater goals.
“From what we are hearing from the commission, they want to mitigate using LID strategies, not just meet the Department of Ecology standards,” he said. “In this instance LID is all about trying to put (stormwater) somewhere other than in a stormwater pipe.”
LaFrance said he believed the commission would recommend to the city council that LID be made a compulsory design standard.
Hamilton said the move to greater employment of LID was being hamstrung by a belief that it was more restrictive, and more expensive.
“Some developers repel from using LID because they don’t understand it,” he said. Hamilton suggested that developers would reap great benefits from using LID in their Town Center plans.
“Of the 240 acres in the Town Center, only 100 of them are buildable, because of the sensitive areas,” he said. “If you reduce that by a further 11 percent, for detention ponds, then you have a significant reduction. The offset of LID is that what you spend on rain gardens, and tanks, you reduce in building ponds.”
Hamilton used the Highpoint development in West Seattle as an example of residential projects using LID to greatly reduce their financial investment in detention ponds.
Planning Commissioner Mahbubul Islam said one of the strengths of collection tanks was that it enable water to be stored and used when it was needed.
“Here obviously most of the rain falls in the winter time, when we don’t really need it for things like gardening,” he said. “But tanks allow us to store the water, and then use it in the summer time.”
He said that new construction would enable tanks to be included as part of the original designs.
“As the new buildings are built in the Town Center, developers can make sure plumbing construction is consistent with rainwater harvesting,” he said. “There won’t be a whole lot of retrofitting needed.”
On Thursday night, following The Reporter’s deadline, the commission was expected to finalize their policy direction on rainwater harvesting, and consider whether the city’s code and ordinances should be amended to encourage their use in the new development.
Not all good news
It wasn’t all good news for the city’s stormwater managers however.
The planning commission learned 2 years of data on two Plateau wetlands had been lost, when the company hired to do studies on them
City of Sammamish Senior Stormwater Program Engineer Eric LaFrance said that he contracted Geotivity, a Canadian company, to record flows and depths at wetland 61, and the wetlands adjacent to Ebright Creek.
They had recorded about 2 years of data before it was announced on Sept. 16, 2008, that the Bank of Nova Scotia had appointed a North Vancouver based law firm as the receiver of Geotivity Incorporated and Geotivity Limited.
The City of Sammamish, and a number of other Geotivity clients, have not been able to retrieve any data since bankruptcy proceedings began.
LaFrance told the planning commission last week that he had requested money in next year’s draft budget for continued monitoring of wetland 61.
