Magnitude of Sources and Pathways in SRRTTF Tech Track Work Group Memo
Explore the draft memorandum by Dave Dilks from the SRRTTF Tech Track Work Group, detailing uncertain but insightful findings on sources and delivery mechanisms of legacy PCBs, with emphasis on building sources and various environmental pathways. The document discusses magnitudes generated from site-specific data and literature, outlining the dominant sources and mechanisms. Challenges in quantifying transport mechanisms are highlighted, alongside conflicting information on tributary loads and the significance of different pathways.
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Presentation Transcript
SRRTTF Tech Track Work Group: Draft Magnitude of Sources and Pathways Memorandum Dave Dilks April 6, 2016
Summary Magnitudes generated from a combination of site-specific data and literature Findings Results are uncertain, but still useful Legacy PCBs in buildings and surface soils are dominant sources WWTPs, tributaries, groundwater, and MS4 are dominant delivery mechanisms Difficult to quantify most intermediate transport mechanisms
Sources Source Category Legacy Building sources Environmental Industrial equipment Ongoing Inadvertent production Non-Local Environmental Lake Coeur d Alene Atmospheric PCB Mass 23,000 kg 5,500 kg x 0.86 kg/year 0.096 kg/year Unknown
Delivery Pathways Source Category PCB Loading Rate (mg/day) 263 Upstream sources Atmospheric deposition to surface water Groundwater loading MS4 stormwater/CSOs Tributaries Municipal and industrial WWTPs Fish hatcheries Bottom sediments <0 149 38 227 299 Unknown 1.22
Delivery Pathway Comments Conflicting information on tributary loads Little Spokane SPMD data suggests large; CLAM data says small Latah Creek Ecology studies suggest small; SRRTTF data says large Lake Coeur d Alene Large load, but at low concentration Bed sediment contribution likely small
Intermediate Pathway Comments Mobilization of building sources dominates Demolition/volatilization of fixed sources Disposal of non-fixed sources Many pathways not readily quantified Contribution from UIC wells Atmospheric sources
Task Force Review Many numbers based on literature values and/or assumptions Openly accepting more site-specific data and/or better assumptions Comments requested by April 26
