NY.gov Portal State Agency Listing Search all of NY.gov
D E C banner
D E C banner

Long Term Control Plan (LTCP) Requirements

If the best management practices (BMPs) alone will not result in compliance with the Clean Water Act (CWA), DEC includes additional controls through the requirement of a Long Term Control Plan (LTCP).

A Long Term Control Plan is a phased approach for control of combined sewer overflows that requires the permittee to develop and submit an approvable plan that will ultimately result in compliance with the NYS water quality standards and Clean Water Act requirements.

NYS permits include the following phased requirements:

Phase I of the long-term control plan is a comprehensive study of the combined sewer system and the effect of combined sewer overflows (CSOs) on the receiving water quality. Once it is determined whether water quality standards in the receiving water are impacted by CSO discharges, if necessary, the permittee will:

  1. Research alternatives for mitigation of the impact of CSO discharges and choose one or more of those alternatives for implementation.
  2. Suggest a schedule of construction or implementation of those alternatives, i.e., Phase II of the long-term control plan, to DEC.
  3. Perform post-construction monitoring, once the control measures are in place, to ensure that the goals of the long-term control plan and the appropriate water quality standards are met.

The planning approach consists of three major steps: system characterization, development and evaluation of alternatives, and selection and implementation of the controls.

The permittee shall develop a Long-Term Control Plan in accordance with the Guidance For Long-Term Control Plan, EPA, September, 1995, which will address the elements contained in Sections A through D below:

I. Phase I

A. Public Participation

The permittee shall prepare and implement a public participation plan that outlines how the permittee will ensure participation of the public throughout the LTCP development process.

B. CSS Characterization

The permittee shall develop and implement a plan that will result in a comprehensive characterization of the Combined Sewer Systems (CSS), including the interceptor sewer system, developed through records review, monitoring, modeling, and other means as appropriate to establish the existing baseline conditions, evaluate the effectiveness of the CSO technology-based controls (BMPs), and determine the baseline conditions upon which the LTCP will be based. The characterization shall adequately address the response of the CSS to various precipitation events; identify the number, location, frequency, and characteristics of CSOs; and identify water quality impacts that result from CSOs.

To complete the characterization, the permittee shall employ the following methods:

  1. Rainfall Records Review - The permittee shall examine the complete rainfall records for the geographic areas of the CSS and evaluate the flow variations in the receiving water body to correlate between the CSOs and receiving water conditions.
  2. CSS Records Review - The permittee shall review and evaluate all available CSS records and undertake field inspections and other necessary activities to identify the number, location, and frequency of CSOs and their location relative to sensitive areas and to pollution sources, such as significant industrial users, in the collection system.
  3. CSO and Water Quality Monitoring - The permittee shall develop a monitoring program that measures the frequency, duration, flow rate, volume, and pollutant concentration of CSOs and assesses the impact of the CSOs on receiving waters. Monitoring shall be performed at a representative number of CSOs for a representative number of events. The monitoring program shall include CSOs and ambient receiving waterbody monitoring and, where appropriate, other monitoring protocols, such as biological assessments, toxicity testing, and sediment sampling.
  4. Identification of Sensitive Areas - The permittee shall identify sensitive areas to which its CSOs occur. These areas shall include waters with threatened or endangered species and their designated critical habitat, waters with primary contact recreation, public drinking water intakes or their designated protection areas and any other areas identified by the permittee or permitting authority, in coordination with appropriate State or Federal agencies.
  5. CSS and Receiving Water Modeling - The permittee may employ models, which include appropriate calibration and verification with field measurements, to aid in the characterization. If models are used, they shall be identified by the permittee along with an explanation of why the model was selected and used in the characterization.

C. CSO Control Alternatives

    1. Demonstrative Approach - The permittee shall develop a range of CSO control alternatives that would meet EPA's requirements for the demonstrative approach. The alternatives should demonstrate each of the following: (1) the planned control program is adequate to meet WQS and protect designated uses, and ( 2) the CSO discharges remaining after implementation of planned control programs will not preclude the attainment of WQS or the receiving waters designated uses or contribute to impairment, and (3) the planned control program will provide the maximum pollution reduction benefits reasonably attainable, and (4) the planned control program is designed to allow cost effective expansion or retrofitting if additional controls are subsequently determined to be necessary to meet WQS or designated uses.
    2. Presumptive Approach - Alternatively, the permittee shall develop a range of CSO control alternatives that would meet one of EPA's criteria for the presumptive approach. These criteria consist of: (1) no more than 4-6 overflow events per year that do not receive minimum treatment; or (2) the elimination or capture for minimum treatment of no less than 85% by volume of the combined sewage collected during precipitation events on a system-wide annual average basis; or (3) the elimination or removal of no less than the mass of the pollutants, identified as causing water quality impairment during the characterization, monitoring, and modeling effort. Minimum treatment for (1) and (2) above is defined as: primary clarification to remove floatables and settleable solids, solids and floatables disposal, and disinfection of effluent, if necessary, to meet water quality standards (WQS) according to 6NYCRR Part 703.
  2. Evaluation of CSO Control Alternatives - The permittee shall evaluate each of the alternatives developed in accordance with C.1 a. or b. to select the CSO controls that will ensure compliance with CWA requirements. The permittee shall consider expansion of the POTW treatment plant(s) secondary and primary capacity as one alternative.
  3. Cost/Performance Considerations - The permittee shall develop and submit cost/performance curves that demonstrate the relationship among the set of CSO control alternatives that correspond to the ranges identified in C.1 a. or b. above.
  4. Identification of the Selected CSO Control Alternatives - The permittee shall submit a description of the alternatives that were considered, the chosen alternative(s) that will be implemented and the reasoning behind the selection.
  5. Schedule - The permittee shall submit a schedule for design and construction of the selected CSO control facilities and/or implementation of other measures. The schedule may be phased based on the relative importance of the adverse impacts on water quality standards and on the permittee's financial capability.

D. Subsequent Requirements

  1. Operational Plan - The wet weather operating plan that is required in the treatment plant's CSO Best Management Practices shall be required to be updated as a result of modifications to the CSS made during the implementation of the LTCP.
  2. Post-Construction Compliance Monitoring Program - The permittee shall develop and submit a post construction monitoring program that (a) is adequate to ascertain the effectiveness of the CSO controls and (b) can be used to verify attainment of water quality standards. The program shall include a plan that details the monitoring protocols to be followed, including CSO and ambient monitoring and, where appropriate, other monitoring protocols, such as biological assessments, whole effluent toxicity testing, and sediment sampling.

II. LTCP Compliance Dates

  1. The permittee shall submit a semi-annual report to the Regional Water Engineer describing the progress/status of the LTCP development, beginning by EDPM + 6 months and continuing every 6 months until Phase II of the LTCP is completed and approved by DEC.
  2. The permittee shall submit the Public Participation Plan to the Regional Water Engineer for review and approval by EDPM + 6 months, which shall be developed in accordance with the requirements in Section I. A. above.
  3. The permittee shall submit the CSS Characterization, Monitoring, and Modeling Plan to the Regional Water Engineer for review and approval by EDPM + 12 months, which shall be developed in accordance with the requirements specified in Sections I. B. above.
  4. Upon DEC approval of the CSS Characterization, Monitoring and Modeling Plan + 24 months, the permittee shall submit a completed Phase I LTCP to the Regional Water Engineer for review and approval, which shall be developed in accordance with the requirements specified in Sections I. B. & C. above:
    1. CSS Characterization Monitoring and Modeling Results
    2. CSO Controls Evaluation and Cost Performance Curves, for all alternatives
    3. CSO Control Alternatives Identification
    4. Proposed Construction and Implementation Schedule, including any supporting analyses

III. Phase II

Upon DEC approval of the Phase I LTCP, the Department will propose a modification to the SPDES permit in accordance with 6 NYCRR - Part 621, to include a schedule of compliance for design and construction and/or implementation of the approved CSO control methods and development of an operational plan and post-construction monitoring in accordance with I. D. above.