DATE:
AUQ 0 7 1995
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION II
SbaJECT: Tutu Wells Site
FROM:
TO:
Shari Stevens, Coordinator ^
Biological Technical Assistance Group (ESD-SMB)
Caroline Kwan, Remedial Project Manager
New York/Caribbean Superfund Branch 2 (ERRD-NYCSB2-E)
As per your request we have reviewed the "Superfund Proposed
Plan," dated August 1995 for the Tutu Wells site in St. Thomas,
U.S. Virgin Islands. We offer the following comments.
As per previous BTAG memos (November 1994 and April 1995), we are
concerned with the potential for groundwater plumes to discharge
into the forested wetland systems in the southeastern portion of
the site. Although the Phase II Remedial Investigation Report
(April 1995) indicates that the majority of the water reaching
the wetland systems will be from surface water runoff, there is
still a potential for groundwater to enter and transport
contaminants to the wetlands through Turpentine Run and
groundwater discharge points. Therefore we are still
recommending that samples be taken in this area. A
characterization of the wetland, including a description of the
type of wetland present, species use, and sediment and surface
water sampling should be completed. Sediment and surface water
analysis should include TCL organics and TAL inorganics.
Previous concerns regarding Mangrove Lagoon, sediment sampling,
and the endangerment assessment (October 1994 BTAG memo) have not
been addressed.
The preferred alternative for groundwater remediation (GRA 4)
includes the installation of groundwater recovery wells and
discharge of treated groundwater to surface water. Due to the
lack of sufficient data regarding the relationship of the
groundwater with the wetland areas, there is concern that pumping
water will lead to a drawdown in the aquifer and subsequently a
reduction in the wetland areas. In addition, if treated water is
discharged to surface water, as opposed to beneficial use, the
affect of this volume of water on Turpentine Run and in-turn the
wetland areas should be reviewed. In order to comply with
federal wetland ARARs, the three parameter method should be used
to delineate wetlands. Also note that a wetlands assessment and
restoration plan will be needed for any wetlands impacted or
disturbed by contamination or remedial activities. Should you
require additional information regarding wetland issues, the BTAG
and/or John Cantilli (212-637-3810) of the Marine and Wetlands
Protection Branch are available for assistance.
REGION II FORM 132O-1 (9/86)
*65033*
65033
The use of a scaling system for hazard indices (His) is
inappropriate (page 6). While the document does cite a USEPA
reference for this system, it is from an Office of Pesticides
Program assessment used for predictive risk modeling in the
process of registering a pesticide. For consideration of
ecological risk at hazardous waste sites, a risk index greater
than one indicates that an effect threshold has been exceeded
(i.e., receptor exposure to contamination exceeds known
benchmarks) and there is potential risk to the ecological
receptor (USEPA. 1992. "Framework for Ecological Risk
Assessment." EPA/630/R-92-001, February). A risk index less than
one means there is a low probability of adverse ecological
effects from site contamination. In addition, although risks to
individual receptors were calculated (page 6), it should be
clearly indicated whether management decisions were based on risk
to individual organisms or risk to a community or population.
Lastly, the remedial action objectives for soil should include
minimizing ecological affects associated with soil contaminants.
I hope these comments are useful to you. If you have any
questions or require further information, please contact Mindy
Pensak at (908) 321-6705.
cc: Carole Petersen, ERRD-NYCSB2
Mel Hauptman, ERRD-NYCSB2-E
Mark Sprenger, HQ-ERT
Gina Ferreira, ERRD-PSB
John Cantilli, WMD-MWPB
Bob Witte, OPM-EIB
Diane Wehner, NOAA
Felix Lopez, USFWS
Karen Kracko, WESTON/REAC