Miller, Jacquelin N.

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University of Hawai'i at ManoaEnvironmental CenterA Unit of Water Resources Research Center2550 Campus Road· Crawford 317 . Honolulu. Hawai'j 96822Tnlephollc: (80B) 95fi-73fil . Pilcsi mi Ie: (608) 956-3980October 8 1996RG:0124Ms_ Kathleen A. DadeyU.S. Army Corps ofEngineersHonolulu Engineer DistrictOperations BranchAttn.: CEPOD-ET-POBuilding 230Fort Shafter. Hawaii 96858-5440Dear Ms. Dadey:Site Management Plan (SMP)The Hawaii Ocean Dredged Material Disposal SitesI have review the draft management plan cited above and offer the following commentsfor consideration by the Corps and Environmental Protection Agency:According to the Draft Site Management Plan (SMP), Section 506 of the WaterResources Development Act of 1992 (WRDA 92) amends section 102(c) of the MarineProtection Research and Sanctuaries Act (MPRSA) of 1972 to require the development of a SMPfor all ocean disposal sites. The contents of the SMP are to include:1. A baseline assessment of conditions at the site;2. Special management conditions or practices to be implemented at the site that arenecessary for protection of the environment;3. Consideration of the quantity of the material to be disposed of at the site, and the presence,nature, and bioavailability of the contaminants in the material;4. A program for monitoring the site;5. Consideration of the anticipated use of the site over the long term, including any need formanagement of the site after the closure; and6. A schedule for review and revision of the plan.An Equal Opportunity/Affirmative Action InstItutionAs you know, I have been involved with the environmental assessment of the South OahuSite (SOS) since 1976 and have recently completed some additional work in the near vicinity ofthe SOS as part of a Corps contract to inventory unexploded ordnance (UXO) in the offshorewaters ofHonolulu. As part of that project, we developed an integrated acoustic (side·scansonar) and fiber optic video imaging system in concert with a differential geographic positioningsystem to search for, locate and identify UXO's. Because the earlier reports ofUXO's offshoreof Honolulu and Pearl Harbors had specifically linked their location with that of dredged materialdisposal prior to )976, our current work provided us with the opportunity to look at old dredgespoil deposits simullaneously while searching for UXO's. The equipment developed as part of theUXO inventory projecl has first order application to virtually all six components of the proposedSMP. Compliance wilh the components of the proposed SMP would be greatly enhanced by useof this equipment at a substantial cost savings (probably of the order of 50% or more) over thecurrent grid system of ground truth sampling based on the results of side scan Olosaiking alone aswas recently employed at the South Oahu Site by the US Geological Survey team. Furthermore,the video work provides reproducible "hard copy" documentation of the conditions at the site atthe time of the survey, making subsequent monitoring work infinitely easier and more accurate.Examples ofllow this video system might be applied to implementation of the proposedSMP are as follows:• direct, real time, visual documentation of geological, physical, and biologicalcharacteristics of the site for both baseline and long term site monitoring;• ability to identify specific areas of interest to minimize costly ground truth sampling (incontrast to the grid system currently being employed by the USGS and other contractedentities monitoring deep water dredged material disposal sites);• reproducible documentation (mapping) of the horizontal distribution of the dredgedmaterials at each site, over time.In addition, recent advances in digital image processing permits even greater extraction ofphysical data from the video images. We are currently exploring the use of various computerimage processing programs to determine which might be feasible to apply to our video images toquantify bedforms, grain size, or biota in the videos.The Monitoring Program (E) described in the draft S:MP mentions that baseline surveys atthe other four Hawaii Ocean Dredged Material Disposal Sites (ODMDS) will be conducted toconfirm the findings and conclusions reached with regard to the likely similarity of those sites withthe Oahu ODMDS. I strongly urge that these proposed baseline surveys make use of the existingvideo technologies in Hawaii so as to minimize the cost of the surveys and maximize the utility ofthe information obtained for long term management purposes. We noted that major bottom reliefin the form of vertical coral heads some 30 meters or more in height are present in areas very nearthe SOS. These vertical difffaces were not detected in the USGS side-scan sonar mapping butwere filmed and documented with our video system.The draft SMP mentions that the results of the USGS studies of the South Oahu Siteconfirmed that the dredged materials remained where originally disposed and that little wasresuspended and transported by bottom currents. Our videos suggest that may not be the case.The video images gave no indication of large mounds of consolidated dredged materials but didsuggest a blanketing effect as would be expected from the disposal of materials acquired by asuction dredge, as used in the major dredging events ofPearl and Honolulu Harbors.Furthermore, we find direct, irrefutable evidence of strong bottom currents, well developedbedforms, and evidence ofscour around larger pieces ofdebris throughout the area offshore fromHonolulu and Pearl Harbors. \Vhile the material may not be re-suspended by the bottom currentswhich have been measured at speeds up to a knot (Chave and Miller, 1977), it is highly possible,and we believe likely, that much of the fines are carried great distances. Support for this belief isalso provided by the grain size analysis of the cores taken by both our studies in 1976-]978 andthe more recent cores taken by the USGS which were dominated by sand sized materials (>70%in most cases) just the reverse of the grain-sized composition of materials taken from the dredgeitself which were more often 70% clay and silt and only 20-30 percent sand sized. Furthermore,because the bottom of Mamala Bay is so littered with recent and past dredged materials, it seemsquite impossible to state with certainty that the material is not being resuspended or transportedby ocean currents during its fall.Nothing in these comments should be construed to suggest that significant impacts arelikely to occur with continued disposal at the Hawaii Sites. However, except for the South OahuSite, insufficient recent information is available to evaluate potential impacts at the other 4 sites.Ifbaseline monitoring of the other 4 sites is to be undertaken, as is stated in the SM:P, then 1would most strongly urge that video mapping of each disposal site and their immediate environscoupled with differential GPS for precise navigation/location of the video footage be required. Aconcentrated effort to video all of the sites, including the South Oahu Site, would provide acomplete and permanent record of the conditions at each site at the time of taping and provide anabsolute, tangible and quantifiable baseline against which subsequent comparisons could be madeas part of a monitoring program. Should ground truth samples be needed, their precise locationcan be determined from an examination of the video footage, thus permitting specific habitat typesto be sampled, not the costly ,multiple, hit and miss sampling required for statistically validrandom or grid pattern efforts.I appreciate the opportunity to provide commenls on the draft SMP and would be pleasedto answer any questions you may have on the various points of my review.Sincerely, ...~L,?J.y~'JJacquelin N. MillerAssociate Environmental Coordinatorcc: Allan OtaRoger Fujioka

Site Management Plan (SMP), The Hawaii Ocean Dredged Material Disposal Sites

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Site Management Plan (SMP), The Hawaii Ocean Dredged Material Disposal Sites

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