
[Federal Register Volume 79, Number 75 (Friday, April 18, 2014)]
[Notices]
[Pages 21918-21919]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-08925]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-9909-75-OW]


Stakeholder Input; Experts Forum on Public Health Impacts of 
Blending at Publicly Owned Treatment Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency is announcing plans to 
hold a forum of public health experts in June 2014 to discuss the 
public health implications of discharges of `blended' effluent from 
publicly owned treatment works (POTWs) served by separate sanitary 
sewers into waterways. The discussion will include public health 
implications of such discharges.
    Today's notice asks for recommendations of public health experts 
who would be interested and qualified to participate in the forum. In 
addition, today's notice seeks recommendations of wastewater treatment 
plant design and operation experts to serve as advisors to the public 
health forum participants. Today's notice also provides the public with 
an opportunity to submit data regarding the performance of municipal 
wastewater treatment plants during wet weather conditions.
    Blending is a practice used by some POTWs to manage wastewater when 
flows to the plant exceed the capacity of the secondary treatment 
units, which happens most often during wet weather conditions. POTWs 
engaged in the practice of blending divert excess flow around secondary 
treatment units and subsequently blend the diverted flows to the 
portion of flow that received secondary treatment. In some cases the 
diverted flows receive some additional treatment before blending. The 
Agency is interested in evaluating the public health implications of 
different blending scenarios, including scenarios where the diverted 
flow is subject to supplemental physical/chemical treatment prior to 
blending and where the diverted flows do not receive any additional 
treatment prior to blending.
    The Agency is undertaking this outreach to help advance the Clean 
Water Act (CWA) objective to restore and maintain the chemical, 
physical and biological integrity of the nation's waters (CWA, Section 
101(a)).

DATES: Suggestions on experts should be made on or before May 4, 2014. 
Other technical information requested in this notice should be provided 
on or before May 19, 2014. We expect to hold the public health forum 
during June of 2014.

ADDRESSES: Submit your recommendations for experts or other input by 
one of the following methods:
     Email to weiss.kevin@epa.gov.
     Mail: Kevin Weiss, Water Permits Division, U.S. 
Environmental Protection Agency, Room 7421J EPA East, 1200 Pennsylvania 
Avenue NW., Washington, DC 20460.

FOR FURTHER INFORMATION CONTACT: EPA will post the date and location of 
the public health experts' forum at: www.epa.gov/npdes/peakflowsforum.
    For further information about this notice, contact Kevin Weiss, EPA 
Headquarters, Office of Water, Office of Wastewater Management at tel.: 
202-564-0742 or email: weiss.kevin@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Background

    Wastewater collection systems collect wastewater from homes and 
other buildings and convey it to wastewater treatment plants for proper 
treatment and disposal. The collection and proper treatment of 
municipal wastewater is vital to the public health in our cities and 
towns and to the viability of our receiving waters.
    During and immediately after wet weather events, flows to 
wastewater collection systems and to treatment facilities typically 
increase. Significant flow increases in a wastewater collection system 
can cause overflows of untreated wastewater and sewage backups into 
buildings. For some municipalities, an important component of their 
strategy to reduce collection system overflows and backups into 
buildings is to increase the conveyance of wet weather flows to a 
treatment plant. Significant increases in flow at the treatment 
facility can cause operational challenges, especially for biological-
based secondary treatment units. Activated sludge systems are 
particularly vulnerable to high volume peak flows. Peak flows that 
approach or exceed design capacity of an activated sludge unit can 
shift the solids inventory from the aeration basin to the clarifier(s), 
and can result in excessive solids losses from the clarifier(s). If a 
clarifier experiences excessive loss of solids, treatment efficiencies 
can be lowered for weeks or months until the biological mass in the 
aeration basins is reestablished. In addition to these hydraulic 
concerns, wastewater associated with peak flows may have low 
concentrations of oxygen-demanding pollutants, which can also decrease 
treatment efficiencies. Biological nutrient removal processes typically 
have an increased sensitivity to the hydraulic and loading fluctuations 
associated with wet weather flows.
    Design and operational options that are routinely employed to 
maintain the effective capacity of biological-based secondary treatment 
units include:
     Providing alternative feed patterns in the aeration 
basin(s);
     Increasing the returned activated sludge rate relative to 
those needed for steady flow;

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     Increasing the size of secondary clarifiers; and
     Damping peak flows to biological-based secondary units by 
providing flow equalization (i.e. storage) prior to the biological-
based secondary unit either at the plant or before flows get to the 
plant.
    These options may temporarily decrease treatment efficiencies for 
the biological-based secondary treatment units and may have limited 
applicability to biological nutrient removal processes. As a result, 
there are limitations on the variation in flow volumes and influent 
strength that biological-based secondary treatment units can 
accommodate.
    Many POTW treatment plants have been designed with primary 
treatment capacity that is significantly greater than the biological-
based secondary treatment capacity. These plants typically provide 
screening and primary clarification of all flows entering the plant. In 
order to protect biological-based secondary treatment units during wet 
weather events, flows that exceed the capacity of the biological-based 
secondary treatment units are diverted around the biological-based 
secondary treatment units after they receive primary treatment. At some 
treatment facilities diverted flows are disinfected and discharged 
directly to a surface water from a separate outfall. Other facilities 
blend the diverted flows with flows that receive biological-based 
secondary treatment and discharge the combined flow after it has been 
disinfected. Some facilities provide some additional treatment of the 
diverted flows while other facilities provide no additional treatment, 
other than disinfection.
    Operators of treatment facilities have several design and 
operational options that can be used to increase pollutant removals 
during high flow conditions, including:
     Adding chemicals to the primary treatment process that 
increase solids removals;
     Providing additional primary treatment capacity, thereby 
lowering overflow rates in the facility's primary treatment units;
     Providing structural changes to primary treatment units, 
such as the installation of lamella settlers;
     Providing supplemental side stream physical/chemical 
treatment units, such as high rate clarification systems or fine screen 
systems, to provide supplemental treatment to flows that are diverted 
around biological-based secondary treatment units.
    EPA is particularly interested in the relative risks associated 
with pathogens, sediments, nutrients, pharmaceuticals, toxics and other 
contaminants that may be discharged under blending scenarios.
    EPA is seeking nominations of public health experts to participate 
at a forum to discuss these issues. The experts should be nationally 
recognized in the fields of evaluating the risks associated with 
various levels of water quality and/or of effluent from wastewater 
treatment plants. EPA, in consultation with key stakeholders, will 
identify wastewater treatment plant design and operation experts to 
serve as advisors to the public health forum participants. EPA is 
soliciting nominations for these experts as part of this Federal 
Register notice.
    After EPA selects the participants it will provide the participants 
with more detailed information to read prior to the forum and will 
provide specific questions on which participants will be asked to 
provide input.

II. Purpose of Public Health Experts' Forum

    The purpose of this forum is to enlist public health experts from 
federal agencies, local health departments and academia in an effort to 
ensure that EPA has appropriate health-based information associated 
with different engineering options available to address wet weather 
blending at POTWs served by separate sanitary sewers. EPA does not 
intend that this meeting be a forum for debating the application of the 
Agency's bypass regulation at 40 CFR 122.41(m) going forward. Rather, 
this forum is solely concerned with the potential public health impacts 
of blended discharges from POTWs.
    Further, it is not EPA's objective during the forum to establish 
consensus among the parties or to obtain a collective set of 
recommendations. Rather, it is EPA's intention to obtain individual 
input from knowledgeable experts so that the Agency can better 
understand the differences and commonalities among the individual 
recommendations. In this regard, EPA has determined that this workshop 
is not subject to the requirements of the Federal Advisory Committee 
Act. 5 U.S.C. Appendix 2.

III. Additional Information on the Forum

    EPA plans to schedule the forum in June, 2014. Information 
regarding the date and location of the forum, along with other 
logistics information, when available, will be posted at www.epa.gov/npdes/peakflowsforum.
    Members of the public are invited to participate as observers in 
the forum as capacity allows. Additional details concerning the 
participation of observers will be posted on this Web page when the 
location and time of the forum is set.

    Authority: Clean Water Act, 33 U.S.C. 1251 et seq.

    Dated: April 9, 2014.
Andrew D. Sawyers,
Director, Office of Wastewater Management.
[FR Doc. 2014-08925 Filed 4-17-14; 8:45 am]
BILLING CODE 6560-50-P


