Seattle Sun Newspaper - Vol. 7, Issue 1, January 2003
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Is Greenwood sinking?
By JAMES BUSH
Is the earth moving under Greenwood's feet?
Diann Knezovich thinks so: since early summer the ground under her Palatine Avenue home has sunk, cracks have appeared in walls, and the gates in her yard are stuck shut. Meanwhile, two large street sinkholes have appeared less than a block away and the sidewalks of two buildings at the corner of Greenwood Avenue North and North 87th Street have started to buckle.
She thinks the culprit could be the millions of gallons of water that construction crews have pumped from the construction site for a new Safeway store at 8704 Greenwood Ave. N.
Knezovich cites a ground water-fed pond on a neighbor's property that was always filled to overflowing, until the water level dropped several feet this summer. She also references city environmental documents from past drainage projects which warned of dire consequences if the groundwater level is significantly altered.
The upper Greenwood neighborhood is built on the site of a former swamp, so the ground includes layers of peat, which can compress when water is removed, causing ground movement.
And there's no question that Safeway has pumped a lot of water into the city's sewer system 4.3 million gallons by mid-October, according to Seattle Public Utilities (at a cost to the company of $27,756 for sewer charges).
After weeks of investigation, Seattle's Department of Design, Construction, and Land Use is finally starting to take notice. DCLU spokesman Alan Justad says that the City has asked Safeway to prepare a new report directly addressing the amount of water being pumped from the site, including recommendations for long-term handling of the water and possible mitigation measures. They are also asking Safeway to monitor existing cracks in surrounding streets caused by construction.
Safeway also isn't the only recent development in the neighborhood. Across the street from the construction site (and backing on Knezovich's property) is a new Walgreen's Drug Store at 8701 Greenwood Ave. N. On the corner to the south is the Towers on Greenwood, a six-story mixed-use building at 8551 Greenwood Ave. N. Both were built within the last two years.
According to city land-use records, both properties contain similar or larger peat concentrations than the Safeway site. In the soils study on file with DCLU, the builders of the Towers on Greenwood project estimated that one or two sump pumps operating around the clock would be needed to de-water the site. The Walgreen's site had even greater groundwater concentrations. Engineers noted water seeping from the ground at one corner of the site. One test boring had to be abandoned due to a continual flow of water from the ground.
Other property owners have seen effects from the earlier construction. Carol Cotey-Watt, manager of the Baranof Restaurant at 8549 Greenwood Ave. N., says her basement floor and front sidewalk sank dramatically after construction of the Towers on Greenwood. "They did the same thing Safeway did they pumped out all the water," she says.
Barrett Jones, who rents a storefront directly across the street from the Baranof, says the front of his building sank four inches during construction of the Towers on Greenwood and has dropped another inch during the last few months.
John Moen has become an unwitting student on the topic of earth movement he's one of 10 Everett homeowners considering a lawsuit against a Safeway in Everett over property damage they suspect was caused by the construction of a nearby store. His neighborhood is built on the site of a filled lake, with deposits of peat up to 30 feet thick. "This peat is like a sponge," he says. "It needs to have water in it to make the peat consistent." And, like a sponge, when it dehydrates, it shrinks.
Moen, who purchased his family home from his parents, says in the 50 years he has lived there, there has been some gentle setting, but nothing on the scale which occurred during and after the Safeway construction.
But proving cause and effect in regards to construction-related impacts can be tough, states Bob Holtz, a geotechnical engineer and University of Washington professor. Lowering the ground water level could cause settling or other problems, he says, but without extensive testing, it's hard to blame the damage on a specific project.
Seattle DCLU spokesman Justad stresses that the city didn't anticipate the large scale of the water pumping at the Greenwood Safeway site, but regulators seem to have missed clues in the land use record.
The environmental checklists (prepared by the developer) for all three Greenwood projects gave a simple "no" in response to the question "Will groundwater be withdrawn?" As a result, the environmental determinations for all three projects contained no restrictions on groundwater removal.
Yet in the case of both the Safeway project and the Towers on Greenwood, later soils reports stated directly that the sites would be de-watered during excavation.
Likewise, if the neighborhood has a history of soil instability (as Knezovich has been told more than once by city employees), why were all three developers allowed to answer "no" to this checklist question: "Are there surface indications or history of unstable soils in the immediate vicinity?"
Knezovich has corresponded with Safeway officials, but the company has admitted no fault in the problems on her property. A Safeway spokeswoman was invited to comment for this article, but didn't call back.
Perhaps part of the problem is the DCLU's new focus on design review over environmental review. Although neighborhoods such as Greenwood have been developed for decades, environmental challenges can be lurking just below the surface.