DOH Summary of Hawaii Kai Dredge Material Analysis 2/4/14

From: Whelen, A. Christian
Sent: Tuesday, February 04, 2014 1:55 PM
Subject: RE: Questions Re: Sludge

Aloha Senator Shimabukuro, Councilmember Pine, Representative Jordan, and Representative Awana:

Attached [see below] please find reports associated with the Hawaii Kai dredged material that was deposited on Waianae property. Acting Director Gary Gill plans to attend the Waianae Neighborhood Board meeting this evening, and wanted to share these reports with you in advance of discussing with the public. He plans to share information in summary form (also attached).

Respectfully,
A. Chris Whelen
Acting Deputy Director, Environmental Health
State Labs Administrator
Hawaii DOH

Department of Health Summary of Hawaii Kai dredge material analysis
February 4, 2014

Sample site (before)

Sample site (before)

Dredge material

Dredge material

Summary:

  • Testing from 3 laboratories (UH, State Labs, and Test America) confirmed a high salinity of the dredge material (53-60,000 mg/kg versus 376 for comparable garden soil).
  • The low rainfall of the area (20-30 inches per year) and lack of nearby, freshwater habitats suggests that saline water from the dredge material during rain events is unlikely to pose a significant runoff problem.
  • The site lies at the mauka edge of basal and caprock groundwater that is not considered to be a viable source of drinking water. This and the low rainfall suggest that leaching of salt from the dredge material is unlikely to cause significant impacts to the beneficial use of the underlying groundwater.
  • The testing also suggests that the dredge material is too saline to support plant life. If vegetation is desired or required in the area, the soil will either have to be capped with non-saline soil or removed.
  • Mixing of non-saline soil with the dredge material (e.g., 50:50 mix) is unlikely to adequately reduce the salt content to levels needed for normal plant growth.
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