Page 86 - Water and wastewater engineering

GENERAL WATER SUPPLY DESIGN CONSIDERATIONS 2-29

TABLE 2-13
Examples of sources to be investigated during the sanitary survey
Surface water Groundwater
Land use and zoning Land use and zoning
Local geology and soils Local geology and soils
Cultivated areas Cultivated areas
Orchards Orchards
Pastures Pastures
Bathing areas Raw materials storage
Gross erosion Landfills
Marinas Septic tank tile fields
Septic tank tile fields Well logs
Sewer outfalls
Storm water drains
Swamps
Upstream tributaries
Vegetation

at least 25 or more people daily for at least 60 days out of the year. The SDWA defines two
types of public water supply: community and noncommunity. A community system serves a
residential, year-round, population greater than 25 people or 15 living units. A noncommunity
system is one that is not a community system but that serves not fewer than 25 individuals on an
average daily basis for not less than 60 days per year. The noncommunity systems are further
separated into two groups: transient and nontransient. The transient systems serve intermittent
nonresidential users. Examples are campgrounds and restaurants. Nontransient systems are non-
residential systems that routinely serve the same individuals. Schools and places of business are
examples of this category.
From 1975 through 1985, the EPA regulated 23 contaminants in drinking water supplied by
public water systems. These regulations are known as National Interim Primary Drinking Water
Regulations (IPDWRs). In June of 1986, the SDWA was amended. The amendments required
EPA to set maximum contaminant level goals (MCLGs) and MCLs for 83 specific substances.
This list included 22 of the IPDWRs (all except trihalomethanes). The amendments also required
EPA to regulate 25 additional contaminants every three years beginning in January, 1991 and
continuing for an indefinite period of time.
Table 2-14 lists each regulated contaminant and summarizes its adverse health effects. Some
of these contaminant levels are being considered for revision. The notation “TT” in the table
means that a treatment technique is specified rather than a contaminant level. The treatment tech-
niques are specific processes that are used to treat the water. Some examples include coagulation
and filtration, lime softening, and ion exchange. These are discussed in Chapters 6 through 14.

Lead and Copper. In June 1988, EPA issued proposed regulations to define MCLs and MCLGs
for lead and copper, as well as to establish a monitoring program and a treatment technique for
both. The MCLG proposed for lead is zero; for copper, 1.3 mg/L. The MCL action levels, appli-
cable to water entering the distribution system, are 0.005 mg/L for lead and 1.3 mg/L for copper.