1 / 14

BACKRIVER TMDL PROJECT

BACKRIVER TMDL PROJECT. Technical Outreach Prepared by MDE/TARSA Prepared for the Baltimore Harbor Stakeholder Advisory Group September 10, 2002. Maryland 303(d) list identification:. The impairing substances on the 1998 303(d) list: Zn Toxics (PCB)

virginia-gallagher
Download Presentation

BACKRIVER TMDL PROJECT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. BACKRIVER TMDL PROJECT Technical Outreach Prepared by MDE/TARSA Prepared for theBaltimore Harbor Stakeholder Advisory Group September 10, 2002

  2. Maryland 303(d) list identification: The impairing substances on the 1998 303(d) list: • Zn • Toxics (PCB) • Sampling data shows Zn is not a problem in Back River

  3. Data Assessment • Data used include: • Physiographic data: describe the physical conditions of the watershed • Environmental Monitoring Data: identify potential pollutant sources and their contribution, and in-stream water quality monitoring data

  4. Inventory of Data

  5. General Trend for Monitoring to Estimate Loads Timing: Winter – wet and dry (Water and Sediment) Spring – wet and dry (Water and Sediment) Sampling for: • Storm Water Outfall/In-stream (NPDES) • Point Source Outfall/In-stream (DMR) • Stream Water Quality Data (mainstem & tributaries) • Boundaries • Sediment – Sediment Quality Triad (toxics) • Cross Section/Longitudinal

  6. General Trend for Monitoring to Estimate Loads Number of samples • At least 1+1(QA/QC) samples per site, per event Substance list • Water column sample • Total, Dissolved, POC, DOC, TSS • Sediment Concentration • Total, Dissolved, AVS, SEM, foc • Sediment Toxicity/Benthic (toxics)

  7. Modeling PCBs • The model and approach to develop the TMDL is influenced by the sources of impairment and type of impairment (PCB). • We looked outside traditional sources of water quality data as a new way to tackle a TMDL for potential “legacy pollutants” • There are no obvious point or nonpoint sources of the contaminant under the Clean Water Act

  8. Watershed load Estimation Approach • 3 methodologies considered: • Loads from potential source sites using the universal soil loss equation • Estimating loads on a subwatershed basis using flow data and average subwatershed PCB concentration • Estimating loads from TSS using SWMM

  9. Toxic Modeling Framework for PCB Framework Under Consideration: • BACKTOX model developed by UVA (on-going project) • Bioaccumulation approach • Biota-Sediment Accumulation Factor

  10. BACKTOX Model • 3 different mass balances are represented • A water balance • A solids balance • Contaminants mass balances

  11. BACKTOX Model Cont’d • It includes: • Hydrodynamic model – CH3D • Sediment transport model • Fate and transport model – Toxiwasp • Also included are sediment layers to account for sediment –water interactions.

  12. BACKTOX Model Cont’d • Linkages: • Linkage to incorporate the hydrodynamic and sediment transport model results into the fate and transport model • Linking the watershed model to the fate and transport model

  13. Bioaccumulation approach • Fish tissue levels are compared to the sediment criteria using Biota-Sediment Accumulation Factor (BSAF) • Tissue level= Sediment conc. *BSAF*unit conversion • Endpoint is based on risk-based PCB fish tissue consumption advisory

  14. TMDL Status • Watershed Assessment (Source/Data Assessment) – Completed • Nonpoint/point source loads – in progress • Endpoint (BSAF) – in progress • Hydrodynamic/Sediment Transport Modeling – at final stage • Linkage – in progress • Toxic model – in progress

More Related