Laboratory Analysis System Administration Potpourri MCLs and MCLGs Backflow Prevention

100

What is DPD (N, N-diethyl-p-phenylenediamine)
This chemical turns pink in the presence of free and/or combined chlorine residual.

100

What is 10 years.
Records of sanitary surveys must be maintained for at least this long.

100

What is schmutzdeke.
This is the technical term for a sticky mat of fine sand and suspended matter that forms on the surface of a sand filter

100

What is 5
The MCL for combined radium in pCi/L

100

What is a Hose Connection Vacuum Breaker
This type of backflow preventer is often used at a mop sink or yard hydrant. They may be quick disconnect.

200

What is carbonate.
Alkalinity consists primarily of this constituent at pH values typical in drinking water systems.

200

What is 5 years
Records of turbidity sample results must be maintained for at least this long.

200

What is direct filtration plants do not have a sedimentation basin.
The primary difference between conventional and direct filtration water treatment plants.

200

What is 15 ug/L
The action limit for Lead

200

What is a Reduced Pressure Assembly
This backflow preventer contains two shut-off valves and two check assemblies that are independently operated.

300

What is apparent color.
This technical term refers to the appearance of a sample before it is filtered. Brown or red are two examples.

300

What is level D
Most groundwater systems treating less than 2 MGD require a certified operator at this level unless chemical treatment or advanced treatment technology is in use.

300

What is 20 psi.
This is the minimum recommended water pressure in a distribution system even during fire flows.

300

What is 250 mg/L
The secondary MCL for chloride

300

What is 2 times the pipe diameter
For an Air Gap type backflow preventer to be effective, the air gap should be at least this big.

400

What is 35 degrees Centigrade
In a presence/absence test, the samples are incubated at this temperature for at least 24 hours.

400

What is positive or greater than zero.
The test results for a finished water sample show a pH of 8.0 and a pH(sat) of 7.5 The Langelier Index will be ________.

400

What is Reduced Pressure Assembly
This type of backflow preventer is required for some high risk connections and cannot be installed in a crawl space or other inaccessible area.

400

What is 500 mg/L
The secondary MCL for Total Dissolved Solids or TDS

400

What is Annually by a certified backflow preventer inspector.
Backflow preventers should be tested, where possible, at least this often.

500

What is Zeta Potential
The charge cloud around a particle in a water sample that determines how particles interact with one another is referred to as this.

500

What is 1,120 units.
Your department uses 80 units of an item per week. You are required to maintain a 10-week reserve of this item at all times and it requires 4 weeks to obtain a new supply. The minimum reorder point is this.

500

What is pH is a log value. You must first take the inverse log of each measurement. Then, add the inverse logs together and divide by the total number of measurements. Finally, take the log of the average.
pH values can't be averaged by adding the values together and dividing by the number of measurements for this reason.

500

What is 0 mg/L
The MCLG for Acrylamide

500

What is none.
This type of backflow preventer can prevent damage to home water heaters from water hammer and/or sudden pressure losses in the distribution system.

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