CSO-Long Term Control Plan – Critical Issues to Consider When Preparing the Technical Guidance Manual for Pre-Treatment /Disinfection

John S. Rolak Jr. (1), Robert Curti (2)

 Hatch Mott MacDonald, 27 Bleeker Street, Millburn, New Jersey 07041, 973-912-2521, 973-912-2632

(1) John.Rolak@hatchmott.com,   (2) Robert.Curti@hatchmott.com

In response to the requirements of the New Jersey CSO General Permit, a Technical Guidance Manual (TGM) must be prepared to assist in the selection of pre-treatment and disinfection controls as part of the CSO Long Term Control Plan.

In preparing this document the Consultant must evaluate the process performance, operation and maintenance requirements and costs of pre-treatment processes such as vortex units, ballasted flocculation, and filters, and disinfection processes such as chlorination (hypochlorite and chlorine dioxide), UV, and UNOX. There are several critical issues which must be addressed during the evaluation to ensure that the results will meaningful to the Client, as well as presenting an accurate estimate of the costs.

The primary critical issues to be considered consist of the following:

• Most of these processes are designed to be utilized in a centralized facility, but instead will be located in remote satellite facilities.
• During combined sewer overflows no available capacity will be available for receiving the treatment process side streams, such as underflows, sludge wasting, backwash water, and flows not receiving adequate treatment as a process starts up.
• The need for, and the sizing of ancillary tankage to store these flows.
• Is there adequate head available for the process headlosses or will some type of intermediate pumping facility be needed.
• How will flows exceeding the capacity of the process be handled, bypassed or stored?
• What are the process limitations in terms of combining processes in series?
• How best to protect the process between events in cold weather?

This presentation will discuss these and other related issues to be considered in preparing the TGM.