Skip to main content

WATER QUALITY AND RISK-BASED PROCESS FOR HYDRAULICALLY SIZING SANITARY SEWER SYSTEMS COMPLIES WITH DRAFT SSO RULE'S LONGTERM REMEDIATION EVALUATION PLAN AND WATERSHED APPROACH

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Since the early 1990s, municipalities have tried to respond to regulatory expectations that:



Construction programs to increase the size of sanitary sewer systems which result in bigger and bigger sewers and treatment plants can eliminate sanitary sewer overflows (SSOs);


Capacity of a system is a technology requirement of the Clean Water Act; and


Engineering designs to ensure water quality in site-specific water bodies is a treatmentonly decision not related to capacity of sanitary sewers.


The draft SSO Rule requires a Capacity, Management, Operations and Maintenance (CMOM) program for each owner and operator of a sanitary sewer system. The wastewater industry understands the role and extent of how MOM can provide for effective capacity in the existing system and prevent SSOs. But the “C” in CMOM stands for capacity and the fundamental issue is: how much capacity is enough?

Under the draft SSO Rule SSOs are prohibited. For the U.S. Environmental Protection Agency (EPA) to consider enforcement discretion or affirmative defenses to an SSO discharge, the cause of the SSO must be attributed to an exceptional circumstance. This protectionist extreme sounds good from a regulatory perspective, but it does not match the real world risk-based decisions that both EPA and the business world believe that public utilities should adopt.

Capacity decisions should be site-specific in nature and based on water quality concerns in the specific water body where and when an overflow may occur. The view that there should never be an overflow from a sanitary sewer is not only physically infeasible (because pipes do leak and there will be a time that groundwater or rainfall will result in an overflow), but the SSO prohibition is also not necessary for every water body across the country in order to protect beneficial uses.

Municipalities should carefully consider the risks of using a capacity standard not related to water quality standards. The model of basing the capacity determinations of the collection and the treatment system on site-specific water quality parameters is consistent with the existing national water quality program. It is recognized that this will require extensive data, analysis and negotiations with the regulators.

A conceptual framework for capacity determination based on water quality in a site-specific water body, at the time that a SSO discharge could likely occur, has been discussed by members of the municipal community. Such a framework could be risk-based, watershed based and provide a basis for permitting SSOs that would not be considered risks.

Another option would be to develop industry-accepted default criteria. Under this mechanism, hydraulic and water quality modeling and analysis to determine how and when a default would be applied to the utility-specific system would be required. Much like the “Presumption” approach of the CSO Policy, however, the industry default would be rebuttal should there be water quality issue in a site-specific location caused by SSOs.

A risk-based, water quality-based approach to “C” coupled with a MOM program will meet the technology and water quality requirements of the Clean Water Act and will focus the long-term remediation evaluation planning leading to cost-effective capacity increases on a site-specific basis.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Document Type: Research Article

Publication date: 2003-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more