3900-PM-BSDW0254e Rev. 2/2013
Module 4
Date Prepared
Date Revised
A.
PUBLIC WATER SUPPLY
MODULE 4 – PRETREATMENT
Permit No.
(For Department Use Only)
PRESEDIMENTATION (PWS Manual, Part II, Section IV.C.1)
N/A
TABLE I
Type of Units
Number of Units
Operating
Volume (Gal)
Total
Where excessively high turbidities are encountered, have studies been made
to determine the feasibility of presedimentation?
Yes
No
N/A
In all cases of high turbidity, has DEP been consulted as to the need for
premixing and settling with chemicals?
Yes
No
N/A
When presedimentation units are provided, has provision been included for
bypassing them?
Yes
No
N/A
4.
Has a minimum detention time of 2 hours been provided?
Yes
No
N/A
5.
Are presedimentation basins equipped with hopper bottoms or continuous,
mechanical sludge-removal apparatus?
Yes
No
N/A
1.
2.
3.
B.
MIXING AND FLOCCULATION (PWS Manual, Part II, Section IV.C.)
N/A
TABLE II
Type of Units
Number of Units
Operating
Volume (Gal)
Total
1.
2.
3.
4.
5.
6.
7.
8.
9.
Are inlet and outlet facilities so designed that short-circuiting is minimized
and that the velocities will enable a good floc to be formed and not be
dispersed upon entrance to the settling basin?
Is a drain provided for the mixing basin or basins with protection against
backflow?
Has DEP approved all discharges of the drainage?
Is there no common wall between water in the mixing basin and water in any
final or filter-effluent storage structure?
Are flash-mixing basins equipped with mechanical, hydraulic or aeration
mixing devices?
Is the detention period of flash-mixing basins from 0.5-2.0 minutes (except
for hydraulic jumps) and the velocity gradient at least 750 fps/ft.?
If a static mixer is provided, the velocity gradient (G) at maximum flow is
fps/ft and at average flow is
fps/ft.
Is the minimum flocculation mixing velocity at least 0.50 feet per second
with a minimum mixing period (considering short-circuiting) of 30 minutes?
In mechanically equipped flocculation basins, is the area of the paddles
from 10 percent to 25 percent of the cross-sectional area of the tank?
4-1
Yes
No
Yes
Yes
No
No
Yes
No
Yes
No
Yes
No
N/A
Yes
No
Yes
No
3900-PM-BSDW0254e Rev. 2/2013
Module 4
Date Prepared
Date Revised
B.
PUBLIC WATER SUPPLY
MODULE 4 – PRETREATMENT
(cont’d.)
Permit No.
(For Department Use Only)
MIXING AND FLOCCULATION (continued)
10. In mechanically equipped flocculation basins, are the agitators driven by
variable-speed motors with the peripheral speed of paddles ranging from 0.5 to
3.0 feet per second?
C.
Yes
No
CHEMICAL APPLICATION (PWS Manual, Part II, Section IV.C.)
N/A
TABLE III
Number of Units
Type of Units
Total
NOTE: If ozone is used in pretreatment, complete Module 8.
1.
Are various points of application of the chemicals provided for flexibility of
operation?
Yes
No
N/A
Is a minimum of two chemical feeders per chemical provided on all water
supplies requiring coagulation?
Yes
No
N/A
Are feeders so located in the treatment plant that chemical dusts will be
prevented from entering the laboratory and operation floor?
Yes
No
Is the capacity and design such that each feeder will be able to supply, at the
maximum rate of flow through the plant, the necessary amounts of chemicals at
an accurate rate for proper treatment of the water?
Yes
No
Is water used for dissolving chemicals protected from any possibility of
backflow of chemical solutions into the safe water supply?
Yes
No
a. Does the safe water supply have an air gap of at least 6 inches or 2 pipe
diameters, whichever is greater, above the maximum water level of any
chemical solution or of water which has not been approved as a public
water supply by DEP?
Yes
No
b. If no, has an appropriate backflow prevention device been installed?
Yes
No
Are feeders’ conveniently located near points of application of the chemical and
easily accessible for maintenance?
Is an adequate containment structure provided for each chemical feed system?
Yes
No
Yes
No
N/A
Are paddles, agitation with air, or other mechanical means provided in the
solution tank to keep uniform strength of solution?
Yes
No
N/A
10. Are solution tanks provided for each chemical of such capacity that each tank
can operate for at least 24 hours?
Yes
No
N/A
11. Is a drain provided for each tank, with protection against backflow?
Yes
No
N/A
12. Are float gauges provided when necessary to indicate the level of solution?
Yes
No
N/A
13. Are chemical feed lines, from the feeder to the points of application, of durable
material, corrosion resistant, easily accessible for dismantling throughout entire
length, protected against freezing and as short as possible in length of run?
Yes
No
2.
3.
4.
5.
6.
7.
8.
9.
4-2
N/A
N/A
3900-PM-BSDW0254e Rev. 2/2013
Module 4
Date Prepared
Date Revised
C.
Permit No.
(For Department Use Only)
CHEMICAL APPLICATION (continued)
14.
D.
PUBLIC WATER SUPPLY
MODULE 4 – PRETREATMENT
(cont’d.)
Is space provided for a minimum of 1 month’s supply of chemicals at a dry
place convenient for the operator’s efficient handling?
Yes
No
SEDIMENTATION (PWS Manual, Part II, Section IV, C.4.)
N/A
TABLE IV
Type of Units
Number of Units
Operating
Volume (Gal)
Total
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Are basins provided with sludge removal equipment?
Are at least two basins provided?
Does the velocity through pipes or conduits from the flocculation (mixing)
basins range from 0.50 to 1.50 feet per second?
Is this velocity reduced at the entrance to the settling basin by baffles or by
directing the water into an enlarged section so that the velocity through the
settling basin will not exceed 1 foot per minute?
Is the basin designed to minimize short-circuiting?
Is the minimum settling period at least 2 hours?
Are outlet devices designed to minimize short-circuiting?
Is the rate of flow over the outlet weir not in excess of 20,000 gallons per
day per foot of weir length?
If submerged ports are used in lieu of overflow weirs, are the ports installed
no more than 3 feet below the flow line?
Are all basins provided with a valved drain?
Are basin bottoms sloped no less than 1 foot in 12 feet toward the drain
when mechanical sludge-removal equipment is not installed?
Is the discharge of drainage from any mixing or settling basin into any
waters of the Commonwealth approved by DEP?
When covers are used, are manholes with raised curbs and covers
provided?
When covers are used, are drop-light connections provided so observations
of the floc can be made at several points?
Are permanent ladders or handholds provided for safety on the inside wall of
the basin above the water level?
Are guard rails provided when tanks are elevated above ground level or
when walk areas are narrow?
Are all flushing lines or hydrants using safe water so constructed, so located,
or so equipped with proper back flow preventers as to prevent any possibility
of backflow into the safe waterlines?
4-3
Yes
Yes
No
No
Yes
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
Yes
Yes
No
No
N/A
Yes
No
N/A
Yes
No
N/A
Yes
No
N/A
Yes
No
N/A
Yes
No
Yes
No
Yes
No