Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
Secondary treatment is required as a minimum treatment, defined as effluent
quality of 45 mg/L BOD5 and 60 mg/L SS. Either BOD5 or CBOD5 may be the permit
criteria. Receiving water quality for rivers and streams is based on a 7 day
consecutive 10 year low flow regime (7Q10). Mass limits for discharges are
usually set using the 7Q10, and average annual plant design flow. Discharge
limits of 10 mg/L BOD5 and 10 mg/L SS may be set in very sensitive environmental
To locate remaining sources of water pollution in water bodies, where quality
is low despite in place pollution controls, the EPA is moving towards total
watershed management by permitting total daily maximum loads (TDMLs) in order to
better control overall pollutant loadings to a watershed. Individual states
identify and develop TMDLS for waters that fail to meet water quality standards
despite pollution controls. Sources can trade TDML allowances.
The EPA National policy on Combined Sewer Overflow (CSO) Control was issued
in 1994 and identifies 9 minimum controls to meet the technology-based
requirements of the Clean Water Act. The CSO National Policy requires
municipalities to develop long-term control plans and lays out targets for CSO
controls to meet water quality standards and Clean Water Act requirements.
Nine minimum controls are:
- Proper operation and regular maintenance programs for the collection
system and CSOs.
- Maximum use of the collection system for storage.
- Review and modification of pretreatment requirements to ensure that CSO
impacts are minimized.
- Maximization of flow to the publicly owned treatment works for treatment.
- Elimination of CSOs during dry weather.
- Control of solid and floatable materials in CSOs.
- Pollution prevention programs to reduce contaminants in CSOs.
- Public notification to ensure that the public receives adequate
notification of CSO occurrences and impacts.
- Monitoring to effectively characterize COS impacts and the efficacy of CSO
The Comprehensive Environmental Response, Compensation and Liability Act
(also known as the Superfund Act) covers wastewater exfiltration and overflow in
the collection system, storage leaks, effluent and solids disposal, if they pose
a threat to public health, welfare or environment.
Individual states develop site-specific water quality standards which mandate
disinfection levels for municipal treatment plants. Guidance is provided by US
EPA and other federal agencies, based upon 50 percent of the fecal coliform
density at which a public health risk has been shown. Presently, if there is no
primary contact with the receiving water, no disinfection or 800 MPN/100 mL
fecal coliform is acceptable. Primary recreational contact with the water
requires 200 MPN/100 mL. Reuse, irrigation and discharge to shellfish waters
requires disinfection to 2.2 fecal coliforms/100 mL.
The most usual statistical basis is a minimum of 5 samples in 30 days.
California has instituted a 7 day median value criteria.
Eighteen (18 ) states have seasonal disinfection requirements only.
The federal government is directly involved in the control of biosolids
management practices, through municipal solid waste landfill regulations (40 CFR
Part 258), technical standards for the use and disposal of biosolids (40 CFR
Part 503), and expanded NPDES programs requiring federal permitting for
biosolids use and disposal (40 CFR Part 122-124 and 501).
The Part 503 technical standards affect generators, processors, users and
disposers of biosolids and domestic septage, and address land application,
surface disposal and incineration.
Land application is defined as biosolids applied to land at agronomic rates
for beneficial use. Biosolids for land application must meet Part 503's heavy
metal pollutant ceiling concentration limits, Class B requirements for pathogen
reduction, and vector attraction reduction requirements. General requirements
and management practices apply unless the biosolids meet high quality pollutant
concentration limits, Class A pathogen reduction requirements and vector
attraction reduction processing requirements.
Surface disposal requirements apply to lined and unlined monofills, dedicated
disposal surface application sites and piles, mounds or lagoons used for final
disposal, defined as longer than 2 years. Metals concentration limits apply for
unlined sites. There are management practice requirements for site location,
control of runoff, methane gas monitoring, crop production, grazing and public
access. States can establish site specific more stringent requirements.
Incineration requirements limit concentrations of heavy metals in biosolids
fed to incinerators, and the concentration of total hydrocarbons or carbon
monoxide in the exit gas from incinerator stacks. Management practices and
frequency of monitoring, record keeping and reporting requirements are also
established. Continuous emissions monitoring equipment, performance tests, and
site-specific air modelling are required.
Facilities in states which do not have a delegated federal program must
comply with both state and federal biosolids management programs.
General Pretreatment Regulations in the U.S. require all publicly owned
treatment works with flows greater than 19 ML/d, and smaller plants with
significant industrial discharges to the collection system, to establish a local
pretreatment program. Explosive, obstructive, excessively variable and
excessively hot pollutants cannot be discharged to collection systems. One
hundred and twenty-six (126) priority pollutants are also regulated by the
General Pretreatment Regulation, and are locally enforced and implemented
through the NPDES permit program. Three hundred and sixty-six (366) extremely
hazardous substances have been identified, and must be traced from point of
generation to disposal if municipal landfills are used for solids disposal, or
if the substance does not mix with the domestic wastewater before it enters the
treatment works. State and local officials must be notified of the presence of
extremely hazardous substances used as part of the wastewater treatment, i.e.:
chlorine and sulfur dioxide, if in excess of specified threshold amounts.
Under the Clean Air Act, emissions of carbon monoxide, particulate, lead,
nitrous oxide, ozone and sulfur oxide emissions from incinerators, dryers,
engines and boilers are regulated. If pollutants defined as hazardous are
emitted at greater than a threshold mass, an air discharge permit is also
Roles of engineering firms, contractors and public agencies
Engineering firms in North America have been instrumental in developing
regulations; providing regulators with the technical background for setting
effluent limits and management guidelines. This work has been undertaken both on
contract and on a volunteer basis, depending upon the situation.
Public agencies such as the Natural Sciences and Engineering Research Council
in Canada and the US Environmental Protection Agency (EPA), and not-for-profit
organizations such as the US based Water Environment Federation Research
Foundation, fund and manage research to extend the detection limits of
laboratory tests, determine toxicity of given substances, and to establish
treatment performance standards.