The Wise Report

The Wise Report

Henry M. Wise, P.G.

February 8, 2008

The TCEQ guidance document, TRRP-24 (Determining PCLs for Surface Water and Sediment), has been updated to reflect the March 2007 revisions to the TRRP rule.  Other minor revisions have been completed as detailed below. The revised document is dated December 2007 and is available from the TCEQ TRRP guidance and forms web page at http://www.tceq.state.tx.us/remediation/trrp/guidance.html 
 

·     Minor text revisions have been incorporated throughout the document as a result of changes to the rule at: §350.37 (i) Human Health Points of Exposure - POEs for surface water runoff or groundwater discharges to surface water; §350.37(k) Human Health Points of Exposure - POEs for sediment; §350.51 (k) Affected Property Assessment; §350.74 (h) Development of Risk-Based Exposure Limits -  Surface water RBEL (changes throughout); Figure: 30 TAC §350.75(b)(1) - Surface Water Exposure Pathway PCL Equation; §350.75(i)(4) PCLs for COCs in groundwater discharge to surface water (SWGW); and Figure: 30 TAC §350.75(b)(1) - Groundwater-to-Surface Water PCL Equation.  
 

·     Section 5.0 (Human Health Pathways not Addressed by the Surface Water RBEL) – This section has been modified to explain the formulas and inputs for the development of the human health contact recreation PCLs for surface water and sediment.  The PCLs have been available (and in use) on the TRRP website for some time.  The text simply provides transparency to the TCEQ’s approach to their development.
 

·     Table 7-3 has been modified to correct a unit discrepancy in the Groundwater Darcy velocity (Ugw) formula so that the Tier 2 dilution factor calculations provided in Figure 7-5, will be correct.
 

·     All hyperlinks have been tested and updated.
 

·     The reference section has been updated as necessary.
TNRCC notations changed to TCEQ.

Henry M. Wise, P.G.

The Wise Report

2/8/2008