Environmental Engineering Homework: Public Water Supply Analysis

This homework assignment addresses key concepts in public water supply, covering topics such as community and non-community water systems, best available treatment technologies, entry points, and point-of-use devices. It explores monitoring requirements, MCLs for contaminants like nitrates, and laboratory certifications for water sample analysis. The assignment also examines sanitary surveys, repeat sampling protocols for microbiological contaminants, and well placement regulations concerning contaminant sources. Specifically, the answers address questions related to different types of water systems, treatment processes, regulatory standards, and the actions required when contaminants are detected. The solutions provide a comprehensive overview of public water supply management and regulatory compliance.

Question 1: What are the two types of pubic water supplies?
Answer: The two types of public water supplies which are as follows:
Community water supplies
A municipal water system (MC).
Other-Than-Municipal water system (OTM)
Non-community water supplies
Non-transient non-community water system (NTNC)
Transient non-community water system (TN)
Note: anything above 6 months is called year round
Question 2: Does a best available technology for treatment take cost into consideration?
Answer: The U.S. environmental protection agency has found “BAT” by analyzing its
applicability in field conditions and not only in laboratory conditions after taking cost into
consideration.
Question 3: What is an entry point?
Answer 3: “Entry point" is a location after treatment/chemical addition in public water system
but before the distribution system.
Question 4: A daycare center is open 10 months of the year with teachers and 54 children
registered to attend. If the daycare center has its own water supply, would it be considered a non‐
transient non‐community water system? If not, what type of system is it?

Answer 4: It will be a non-transient non-community water system as it serves the same people
year round.
Question 5: Would a Brita on Tap Faucet be considered a POE (point‐of‐entry) or POU (point‐
of‐use) treatment device?
Answer 5: It will be treated as POU as POU is the water treatment device used on single tap and
POE is the water treatment device used for the entire house or building.
Question 6: Is a system that uses groundwater under the direct influence of surface water a
groundwater or surface water system?
Answer 6: Public water systems that serve 10,000 or more people which are transient NCWSs
and which use chlorine dioxide as a disinfectant/oxidant.
Question 7: Water suppliers must conduct monitoring. Who may increase monitoring
requirements? Who may decrease monitoring requirements if such a decrease will not adversely
affect the protection of public health?
Answer 7: Water suppliers for public water systems are required to
conduct source water monitoring by collecting samples for each of the plants which is treating a
surface water or GWUDI. When many plants take water from the same influent, like from the
same pipe /intake, then the department can increase or decrease the monitoring requirements.
Question 8: Under NR 809.07 (2) there is a table of MCLGs that are less than the MCL. Are those
levels enforceable?

Answer 8: They are not enforceable only if the department is of the opinion that the action is
important to protect public health and it may require the water supplier for the treatment or may
ask him to replace the water source.
Question 9: When may bottled water be used for a public water supply?
Answer 9: Bottled water shall not be used by the public water supply on a temporary basis if it is to
avoid risk to health.
Question 10: What is the MCL for nitrate? For a non‐community transient system that uses
groundwater, what will the monitoring frequency be for nitrate if the system’s last sample had a
result of 6.2 mg/l?
Answer 10: MLC for nitrate is 5 mg/L nitrate .Our sample had a result of 6.2 mg/l which means, that
the community and non-transient non-community water systems shall repeat the
monitoring frequency for groundwater systems quarterly for minimum one year.
Question 11: Analysis of drinking water samples for inorganic and synthetic organic contaminants is
only conducted by laboratories that have which types of certifications or approval?
Answer 11: The Laboratories involved in the analyses of drinking water samples for inorganic and
synthetic organic shall have the certification for analytes or analyte groups that belong to the
analytical classes as given in Table 4.
Question 12: If a system had a sanitary survey conducted May 3, 2016, what “new” evaluation with
regards to microbiological contaminant monitoring would have been conducted during that
sanitary survey that would not have been conducted during the system’s sanitary survey that was
conducted in 2011?

Answer 12: After April, 1,2016, the department requires a special monitoring with regards to sanitary
surveys. Thus, the water supplier of the seasonal system shall collect compliance samples during
these time periods.
Question 13: If a routine sample for microbiological contaminate monitoring is total coliform-
positive, that means there were bacteria present in the sample. A public water system must
collect repeat samples for each total coliform-positive sample. How many repeat samples must
they collect and how soon must the system collect the samples?
Answer 13: It shall collect a set of repeat samples within 24 hours not less than 3 repeated
samples for each of the total coliform-positive sample found.
Question 14: How often must a non‐community system undergo a sanitary survey?
Answer 14: it shall undergo a sanitary survey every five years.
Question 15: Wells used for extracting groundwater cannot be placed at any location on a
property. The wells must be placed at specific distances from potential contaminant sources. If a
well was drilled on June 23,2016, how far away must it have been from the edge of a stormwater
detention pond?
Answer15: ponds shall be located at least 400 feet from a well.