Prepared for: Alaska Railroad Corporation Anchorage, Alaska Remedial Investigation Alaska Railroad Corporation Anchorage Terminal Reserve U.S. EPA Docket No. CERCLA 10-2004-0065 Volume I – Text and Tables The RETEC Group, Inc. November 2007 – Revision 1: January 25, 2008 Revision 2: May 12, 2008 Document No.: 00092-028 Contents 1.0 Introduction ............................................................................................................................................ 1-1 1.1 Objectives of the Administrative Settlement Agreement and Order on Consent .......................... 1-1 1.2 Preliminary Conceptual Site Models............................................................................................... 1-2 1.3 Approach for achieving investigation objectives............................................................................. 1-3 1.3.1 Areas not specifically addressed in the RI/FS .................................................................. 1-4 1.3.2 RI approaches for protection of Ship Creek ..................................................................... 1-5 1.3.3 Authoritative groundwater, soil, and soil gas evaluation .................................................. 1-6 1.3.4 Terminals Area................................................................................................................... 1-7 1.3.5 Sources of Site information ............................................................................................... 1-8 1.3.6 Leased property review for remedial investigation ........................................................... 1-9 1.3.7 RCRA SWMU/Area of Concern review for remedial investigation .................................. 1-9 1.4 Current and likely future land use ................................................................................................... 1-9 1.5 Prior documents, studies, and interim reports.............................................................................. 1-10 1.6 Report organization ....................................................................................................................... 1-11 2.0 Scope of remedial investigation .......................................................................................................... 2-1 2.1 Data adequacy review..................................................................................................................... 2-1 2.1.1 Ship Creek media data quality objectives......................................................................... 2-2 2.1.2 Groundwater data quality objectives................................................................................. 2-3 2.1.3 Soil data quality objectives ................................................................................................ 2-5 2.2 Data validation summary................................................................................................................. 2-6 2.3 Studies to evaluate physical conditions .......................................................................................... 2-7 2.3.1 Physiography ..................................................................................................................... 2-7 2.3.2 Hydrology and hydrogeology ............................................................................................ 2-7 2.3.3 Land use, land cover, and demographics......................................................................... 2-8 2.3.4 Leased property reviews ................................................................................................... 2-8 2.4 Evaluation and use of pre-RI data .................................................................................................. 2-8 2.5 RI sampling summary.................................................................................................................... 2-11 2.5.1 Ship Creek media sampling ............................................................................................ 2-12 2.5.2 Groundwater sampling .................................................................................................... 2-13 2.5.3 Soil and soil gas sampling............................................................................................... 2-14 2.5.4 Other Site sampling ......................................................................................................... 2-15 2.5.5 Background sampling ...................................................................................................... 2-15 2.6 Studies to provide data for the feasibility study ............................................................................ 2-17 3.0 Site physical characteristics ................................................................................................................ 3-1 3.1 Ship Creek and Cook Inlet .............................................................................................................. 3-1 3.1.1 Ship Creek history ............................................................................................................. 3-1 Revision 1: January 25, 2008 i November 2007 3.1.2 Ship Creek hydrology ........................................................................................................ 3-2 3.1.3 Sediments .......................................................................................................................... 3-3 3.1.4 Classification...................................................................................................................... 3-4 3.1.5 Discharges, outfalls, and storm drainage system............................................................. 3-4 3.1.6 Cook Inlet ........................................................................................................................... 3-7 3.2 Environmental setting ...................................................................................................................... 3-7 3.2.1 Climate and meteorology .................................................................................................. 3-7 3.2.2 Physiography ..................................................................................................................... 3-8 3.2.3 Geology and soils .............................................................................................................. 3-8 3.3 Hydrogeology................................................................................................................................. 3-11 3.4 Land use and demography ........................................................................................................... 3-13 3.4.1 Site property distribution and land use............................................................................ 3-13 3.4.2 Site zoning ....................................................................................................................... 3-14 3.4.3 Site surface cover ............................................................................................................ 3-14 3.4.4 Site groundwater use....................................................................................................... 3-15 3.5 Ecological habitat........................................................................................................................... 3-15 3.5.1 North Bluff ........................................................................................................................ 3-15 3.5.2 Ship Creek riparian zone................................................................................................. 3-16 3.6 Terminals Area focused study....................................................................................................... 3-17 3.7 Refined hydrogeologic Conceptual Site Model ............................................................................ 3-20 4.0 Nature and extent of contamination.................................................................................................... 4-1 4.1 Background investigation ................................................................................................................ 4-1 4.1.1 Surface water..................................................................................................................... 4-2 4.1.2 Sediment ............................................................................................................................ 4-3 4.1.3 Groundwater ...................................................................................................................... 4-3 4.1.4 Soil...................................................................................................................................... 4-5 4.2 Ship Creek media investigation....................................................................................................... 4-8 4.2.1 Ship Creek main channel surface water ........................................................................... 4-8 4.2.2 Off-channel surface water ................................................................................................. 4-9 4.2.3 Ship Creek sediment ....................................................................................................... 4-10 4.2.4 Off-channel areas sediment ............................................................................................ 4-11 4.3 Groundwater and LNAPL nature and extent investigation..........................................................