OAK HARBOR, Wash. - Naval Air Station (NAS) Whidbey Island finished construction on its first sand filter pit as part of a new stormwater management system, Dec. 1.
The Skywarrior Base Theatre parking lot on Ault Field had been expanded and required a sand filter pit to decrease litter and stormwater flow to Clover Valley Creek.
“The reason the sand filter is needed is because the new parking lot has no buffer to slow the flow of water on the surface,” said Jaime Jensen, Naval Facilities Engineering Command (NAVFAC) environmental water program manager. “Water flows much faster on flat hard surfaces into the storm drains and carries all sorts of pollutants.”
Islands included in the parking lot act as catch basins filled with river rock and fledgling trees to assist with infiltration and filtration. This reduces water speed and keeps more water on-site alongside a berm built around the perimeter to prevent overflow.
“As water runs off the buildings it is directed toward the sand filter and any debris such as leaves, and other foreign objects are trapped on top of the sand as water infiltrates through the sand on the way to the creek,” said David Goodchild, NAVFAC construction manager.
Without the construction of the sand filter to sift through pollutants, the stormwater can carry debris to the creek which leads to erosion as it scours the bank.
“Sediment from eroding soils contains organic matter that contributes to oxygen depletion in the water as it is decomposed,” said Jensen. “This is harmful to wildlife and the sand filter can reduce the impact.”
Jensen said that while erosion occurs naturally when an outside element disrupts the current environment, the freshwater animals have to deal with this unfamiliar shift.
“This sand filter pit is an example of the future water structures needed to assist in environmental preservation on NAS Whidbey Island,” said Goodchild.