NOTICES
DELAWARE RIVER BASIN COMMISSION
Notice of Determination Regarding the Assimilative Capacity of the Tidal Delaware River for Toxic Pollutants; Public Hearings
[29 Pa.B. 1091] The Delaware River Basin Commission (Commission) will hold public hearings to receive comments on a determination that the assimilative capacity of the tidal Delaware River is being exceeded for certain toxic pollutants. This determination will authorize the Executive Director to establish wasteload allocations for specific point source discharges of these pollutants.
The public hearings are scheduled as follows:
May 3, 1999 beginning at 1:30 p.m. and continuing until 5 p.m., as long as there are people present wishing to testify.
May 5, 1999 beginning at 1:30 p.m. and continuing until 5 p.m. as long as there are people present wishing to testify; and resuming at 6:30 p.m. and continuing until 9 p.m., as long as there are people present wishing to testify.
May 11, 1999 beginning at 1:30 p.m. and continuing until 5 p.m., as long as there are people present wishing to testify.
The May 3, 1999 hearing will be held in the Second Floor Auditorium of the Carvel State Building, 820 North French Street, Wilmington, Delaware.
The May 5, 1999 hearing will be held in the Goddard Conference Room of the Commission's offices at 25 State Police Drive, West Trenton, New Jersey.
The May 11, 1999 hearing will be held in the Jefferson Room of the Holiday Inn at 400 Arch Street, Philadelphia, Pennsylvania.
For further information contact Susan M. Weisman, Commission Secretary, Delaware River Basin Commission, P. O. Box 7360, West Trenton, New Jersey 08628, (609) 883-9500, Ext. 203.
Background and Rationale
On October 23, 1996, the Commission amended its Comprehensive Plan, Water Code and Water Quality Regulations concerning water quality criteria for toxic pollutants, and policies and procedures to establish wasteload allocations and effluent limitations for point source discharges to the tidal Delaware River.
Specifically, water quality criteria for selected toxic pollutants were incorporated in the Comprehensive Plan and Article 3 of the Water Code and Water Quality Regulations as stream quality objectives. Article 4 of the Water Quality Regulations was amended to include policies and procedures to be used to establish wasteload allocations for those discharges containing pollutants which exceed the stream quality objectives and impact the designated uses of the river following a Commission determination that the assimilative capacity of a zone of the Delaware River is exceeded. These amendments provided a mechanism for identifying toxic pollutants which impair aquatic life and human health, and developing uniform and equitable wasteload allocations for those NPDES discharges to the tidal Delaware River which contribute to their impairment. The permitting authorities of the Basin states will utilize allocations developed by the Commission to establish effluent limitations for NPDES permittees in their jurisdiction, as appropriate.
The subject of the hearings is a proposed determination by the Commission that the assimilative capacity of the tidal Delaware River (Trenton, NJ to the head of Delaware Bay) is being exceeded for 1,2-dichloroethane, tetrachloroethene, chronic toxicity and acute toxicity. These parameters were selected based upon their mass loading to the estuary, minimal interaction with estuary sediments and the availability of calibrated and validated water quality models that could be used to develop the wasteload allocations. This determination will authorize the Executive Director to establish wasteload allocations for continuous point source discharges under sections 4.30.7A.1. and 4.30.7B.2.c. of the Commission's Water Quality Regulations.
Seventy-six continuous point source discharges were considered in each of the wasteload allocation exercises, although the number included in any allocation varied from 10 to 55. The procedure used to develop the wasteload allocations is called Equal Marginal Percent Reduction or EMPR. EMPR is a two step process in which a discharge is first considered independently of all other discharges to the estuary. In this step called the Baseline Analysis, each discharge must meet stream quality objectives in and of itself. In the second step called Multiple Discharge Analysis, the cumulative impact of all discharges, discharging at the baseline loading established during step one, is evaluated against the stream quality objectives. If the analysis indicates that an objective is exceeded, then the baseline loads of all discharges significantly contributing to the violation are reduced by an equal percentage until the stream quality objective is met.
For 1,2-dichloroethane, 11 of 51 discharges were adjusted from their initial loading to meet the stream quality objectives. For tetrachloroethene, seven of 40 discharges were adjusted to meet the stream quality objectives. For chronic toxicity, ten of the 55 discharges were adjusted during the baseline analysis portion of the wasteload allocation. The multiple discharge analysis portion of the procedure will not be implemented for chronic toxicity so that additional data on the relationship between the concentration of specific chemicals and toxicity of both wastewater and ambient samples can be obtained. This portion will be deferred until Phase 2 of the Total Maximum Daily Load (TMDL) is completed.
For acute toxicity, eight of the ten discharges evaluated were reduced from their initial wasteload allocation concentration during the baseline analysis portion of the allocation. As with chronic toxicity, the multiple discharge analysis which will determine the total surface area of the estuary assigned to mixing areas will be deferred until Phase 2 of the TMDL is completed.
In accordance with section 4.30.7B.2.c.5 of the Commission's Water Quality Regulations, a document entitled Wasteload Allocations for Volatile Organics and Toxicity: Phase 1 TMDLs for Toxic Pollutants in the Delaware River Estuary has been prepared which describes the process used to develop wasteload allocations for continuous point source discharges as part of Phase 1 of a Total Maximum Daily Load for selected toxic pollutants for the tidal Delaware River. This document is available on the Commission's web site at www.state.nj.us/drbc, or by contacting Christopher Roberts, Public Information Officer, at (609) 883-9500, Ext. 205.
The following supporting documents describing the mathematical models used in the process are also available from the Commission:
Calibration and Validation of a Water Quality Model for Volatile Organics and Chronic Toxicity in the Delaware River Estuary.
Calibration and Validation of the DYNHYD5 Hydrodynamic Model for the Delaware River Estuary.
Development of a Tidal Version of the CORMIX Models for Application to Discharges in the Delaware Estuary.
Copies of these documents may be obtained by contacting Christopher Roberts, Public Information Officer at (609) 883-9500, Ext. 205.
Persons wishing to testify are requested to notify the Secretary in advance. Written comments on the proposed determination should also be submitted to the Secretary.
Delaware River Basin Compact, 75 Stat. 688.
SUSAN M. WEISMAN,
Secretary
[Pa.B. Doc. No. 99-307. Filed for public inspection February 26, 1999, 9:00 a.m.]
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