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Wastewater Treatment and Disposal

Mission Statement
History
Reports
Permits
  NPDES
  Stormwater
  Air
Recycling/Reusing Treatment Plant By-products
Sewer Rate History (residential)

 

 
To responsibly operate and maintain the wastewater treatment and disposal system of the North San Mateo County Sanitation District in a manner that provides current and future customers with safe, efficient and cost effective wastewater treatment services while protecting the environment from water pollution.
 

Today's treatment plant is on the site of the very first treatment system for the area. A large septic tank served the early population - which grew drastically as survivors of the 1906 San Francisco earthquake and fire sought refuge in Daly City. In 1907, the Spring Valley Water Company, fearing pollution of its water supply, permitted the septic tank overflow to be diverted to the Vista Grande Tunnel for disposal to the Pacific Ocean. The Vista Grande Tunnel was built in 1895 to handle storm water overflow from Lake Merced. The brick, egg-shaped tunnel is still used today to transport treated wastewater from the City's effluent pipeline to the ocean outfall at Thornton Beach.

The area's population took another sharp jump after World War II, as returning veterans bought homes for their families in Broadmoor Village and Westlake subdivisions. To serve the wastewater collection and treatment needs of this growing area, the San Mateo County Board of Supervisors created the North San Mateo County Sanitation District on January 16, 1951. In 1953, voters approved a $600,000 bond issue to finance construction of a primary wastewater treatment plant at the southerly end of Westlake Park. The plant went into operation in August of 1955, serving a population of 30,000.

Artichoke fields and hog ranches continued to give way to houses as St. Francis Heights and Serramonte were completed. In 1975, with funding from the Clean Water Act Grant Program, the plant facilities were upgraded to full secondary treatment. The secondary plant utilized the UNOX pure oxygen, activated sludge process.

On July 1, 1985, the North San Mateo County Sanitation District became a subsidiary district of the City of Daly City. At that time, the plant was nearing its treatment capacity. As interim measures, the City formalized a Water Conservation Program and instituted a moratorium on new sewer connections. Meanwhile, planning began for Daly City's most ambitious public works project ever undertaken.

The treatment plant experiences very high morning and evening peak flows. This is a characteristc common to "commuter communities", but in Daly City the peaks are abnormally high - nearly three times greater than the average daily flows. In 1989 the plant was expanded to equalize the peak flows and provide additional capacity.

 

The expansion featured a unique underground primary treatment and flow equalization system. The $14.7 million underground facilities increase the plant's secondary capacity from 8 to 10.3 million gallons per day. The facilities were designed for underground construction to preserve the residential and recreational setting of the plant site. An existing softball park was temporarily removed during construction. The plant expansion and related landscaping, roadways and lighting, were financed entirely by District-backed Certificates of Participation.
 

The City's collection, treatment and disposal systems serve the majority of the residents of Daly City, along with the Broadmoor Village, a portion of the Town of Colma, the Westborough County Water District in South San Francisco, and the San Francisco County jail in San Bruno.

Daly City's operation of its wastewater system has been widely recognized for its community involvement, dedication to water quality issues, and efficient operation. The City was awarded "Wastewater Treatment Plant of the Year" from the California Water Pollution Control Association, "Award for Excellence in Collection System Operation and Maintenance" from the United States Environmental Protection Agency, as well as awards to individual staff members such as "Treatment Plant Operator of the Year, "Collection System Person of the Year" and "Plant Maintenance Person of the Year".

  Annual Discharge Monitoring Report
  NORTH SAN MATEO COUNTY SANITATION DISTRICT DISCHARGE MONITORING REPORT SUMMARY FOR 1999
  GRAPHIC AND TABULAR SUMMARIES
    Annual Discharge Monitoring Report for 1999
Biosolids Monitoring Report
  NOTICE AND NECESSARY INFORMATION (NANI)
  Regulatory and Policy Background
 
In 1972, under the authority of Public Law 92-500, the Federal Water Pollution Control Act, EPA created the NPDES. This was intended to control discharges to the Nation's waters from industrial, commercial, and municipal point sources; these discharges presented a threat to water quality and public health. Initial efforts focused on traditional pollutant discharges from industrial manufacturing processes and municipal Wastewater Treatment Plants (WWTP).

Later amended to become the Clean Water Act (CWA), this law provides broad authority for EPA or States (authorized by EPA) to issue NPDES permits. Specific reporting requirements are established in the permits to require monitoring and reporting of discharges. The CWA establishes two types of standards for conditions in NPDES permits: technology-based standards and water quality-based standards. These standards are used to develop effluent limitations and special conditions in NPDES permits. Numeric effluent limitations establish pollutant concentration limits for effluents at the point of discharge. Section 402(a)(1) authorizes the inclusion of other types of conditions that are determined to be necessary, known as special conditions, in NPDES permits. Special conditions can include requirements for best management practices (BMPs) to control Wet Weather Flows (WWF).

Since the implementation of the CWA requirements, EPA has begun to address nontraditional sources of pollution, such as those that result from WWF. The NPDES program currently requires permits for point sources, but not for non-point sources (NPS).

Pollutants in WWF discharges from many sources remain largely uncontrolled. The EPA in both its 1992 National Water Quality Inventory (EPA, 1994a) and its 1995 Report to Congress (EPA, 1995a) cited pollution from WWF as the leading cause of water-quality impairment. WWF from both point and non-point sources is one of the largest remaining threats to water quality, aquatic life, and human health that exists today. The National Research Council (1992) concluded that correction of NPS pollution problems is a major priority to surface water protection and should be implemented as part of a large-scale aquatic ecosystem program.

In its National Agenda for the Future, issued on December 30, 1994, two priority areas were cited by EPA in the water program: - protect public health by ensuring that drinking water is safe - protect the environment by improving WWF controls EPA reiterated this in 1996 in the updated "National Water Program Agenda for the Future: 1996-1997".

Over the past two decades, local, regional, and national-scale research programs have shown that pollutants discharged from municipal separate storm sewer systems are among the principal causes of water quality problems in most urban areas. Recognizing this, Congress and USEPA set forth legislation and regulations (respective) that have required public works managers in most sizeable urban areas to focus attention on their storm water collection and conveyance systems. The regulations were intended to get senior management personnel engaged in efforts to consider the following:
  • What are the physical characteristics of our storm water system?
  • Where does it discharge to the local receiving waters?
  • What land uses and activities are served by the system (and contribute pollutants)?
  • What degree of control do we have over those who contribute pollutants?
  • What concentrations and annual loads of pollutants are discharged with our storm water?
  • What do we presently do to minimize those pollutants and their resultant impacts?
For most sizeable municipal public works departments and flood control agencies, the past several of years' efforts to respond to NPDES permitting requirements have been challenging and illuminating; but also frustrating. Most applicants learned things about their systems that will help them be better managers in the future. Most of these applicants are now facing the lack of practical ways to effectively conceptualize and manage large, complex urban watersheds. To do so will require managers to collect and consider large amounts of diverse information on a continuing basis.
 
Meeting Clean Water Standards
 
The treated wastewater (effluent) that our Treatment Plant discharges into the Ocean is subject to stringent water quality standards specified in our discharge permit. This permit-part of a program called the National Pollutant Discharge Elimination System, or NPDES-is issued by the San Francisco Regional Water Quality Control Board. Permits are usually renewed every five years.

Specific discharge standards are determined by the Regional Board on a case-by-case basis and often differ from one wastewater treatment plant to another. For example, a treatment plant that discharges into the Bay or river will have more stringent standards than NSMCSD, which discharges into the ocean.

NPDES permits specify maximum permissible levels for various technical measurements, including the quantity of effluent discharged in wet and dry weather (flow rates), plus Carbonaceous Biochemical Oxygen Demand; Grease and Oil; Suspended Solids; Settleable Solids; Turbidity and Acute Toxicity.

Although no specific discharge limitations have been set, NSMCSD's discharge permit also requires regular monitoring of eighty-three other water quality standards. In addition the discharge permit requires monitoring at the point of discharge into the Ocean. Separate permits address disposal of the solids removed from wastewater and the quality of stormwater runoff.

For more information on NSMCSD's discharge permit, please contact: Cynthia Royer or Kevin Brown at (650) 991-8200 or email them at croyer@dalycity.org or kbrown@dalycity.org
 
NPDES
  Wastewater NPDES Permit NO. CA0037737
  Attachments:
Contingency Plan - Regional Water Board Resolution No. 74-10
Self-monitoring Program
      Part A, Dated August 1993
Part B, Dated February 16, 2000
 
Stormwater
  City NPDES Stormwater Permit
 
Air
 
Keeping Daly City's Air Clean
In the San Mateo County area, the Bay Area Air Quality Management District (BAAQMD) regulates emissions of smog-producing chemicals. Other regulatory agencies include the California Air Resources Board and the U.S. Environmental Protection Agency. These agencies establish limits on smog-related chemicals produced by a variety of combustion sources. NSMCSD's principal combustion sources are:
  • Digester gas flares and boilers used in wastewater treatment processes, and
  • Diesel-powered generators and pumps that keep critical water and wastewater pumping stations operating during extended power failures, ensuring uninterrupted service to our customers.
 
PERMIT TO OPERATE
Issued by BAY AREA AIR QUALITY MANAGEMENT DISTRICT

NSMCSD is committed to protecting our environment. We endeavor to recycle and reuse the treated by-products of our plant, namely, treated wastewater effluent and biosolids. California's limited water supply will pose greater challenges for our future, and the NSMCSD, in cooperation with others, will look for new ways to reuse water. The NSMCSD reclamation program began in the late 1980s in response to the drought and continues today to conserve a precious resource. We also make sure that our biosolids are put to good use for safe land application and soil amendment. Reuse completes the cycle that leads to a sustainable future.
 
  Recycled Water
 
Water Recycling - a responsible solution to the growing demand for water
Recycled water is a smart alternative water supply source for the Daly City area due to its limited groundwater supply and increasing population. By using recycled water for non-potable (non-drinkable) uses such as irrigation, precious drinking water supplies can be conserved. Since the mid eighty's the NSMCSD has been installing recycled water pipes around the City when water or sewer projects are constructed.

Our Water Irrigates Nearby Landscapes
Currently, our recycled water is used to irrigate landscaped medians in the Westlake area. A study is being conducted to use our recycled water to maintain the level of Lake Merced and eliminate the use of potable groundwater to accomplish optimum level. It is also being used for various uses at the wastewater treatment plant. Plainly marked purple pipelines, completely separate from drinking water systems, deliver the water to use sites. Water recycling is a safe and proven practice. For many years, recycled water has been safely used for landscape irrigation purposes throughout California and the world saving several million-acre feet of precious potable water for other uses.
   
  Biosolids
 

The NSMCSD's treatment process produces approximately 6 tons of dry sludge per day, all of which is recycled. During the rainy season the biosolids are used as daily cover at Redwood Landfill in Novato. During the spring and summer months it is used as a soil amendment for non-edible food crops in Solono County.

 
 

Date

Approved

Ordinance

Number

Old Rate

% Increase

(Decrease)

New Rate

Minimum

Charge

7/12/99

84

$ 2.90

5.0

$ 3.05

$ 36.96

7/14/97

83

$ 2.83

2.5

$ 2.90

$ 36.96

6/12/95

82

$ 2.75

3.0

$ 2.83

$ 36.96

6/12/93

81

$ 2.95

(9.0)

$ 2.75

$ 28.00

6/13/92

76

$ 2.40

22.9

$ 2.95

$ 28.00

5/1/91

75

$ 1.96

22.0

$ 2.40

$ 28.00

6/26/89

73

$ 1.66

18.1

$ 1.96

$ 25.50

6/27/88

71

$ 1.54

7.8

$ 1.66

$ 25.22

7/13/87

70

$ 1.48

4.1

$ 1.54

$ 23.40

6/23/86

65

$ 1.31

3.0

$ 1.48

$ 22.50

5/25/85

61

$ 1.28

2.3

$ 1.31

$ 18.00

5/18/84

59

$ 1.25

2.4

$ 1.28

$ 18.00

5/23/83

57

$ 1.20

4.2

$ 1.25

$ 18.00

5/25/82

54

-

-

$ 1.20

$ 18.00