========+==============================+============
| ~Bacteria.~ |~Coagulant.~
+---------+----------+---------+------------
Date. | Applied | Effluent,|Effluent,|Grains, per
| water. |coagulant.| sand. | gallon.
--------+---------+----------+---------+------------
1907.
--------+---------+----------+---------+------------
Feb. 12| ... | ... | ... | ...
Feb. 13| 600 | ... | ... | ...
Feb. 14| 650 | ... | ... | ...
Feb. 15| 600 | ... | 2,500 | ...
Feb. 16| 850 | ... | 1,600 | ...
Feb. 17| ... | ... | ... | ...
Feb. 18| 1,200 | ... | 300 | ...
Feb. 21| 1,800 | ... | 550 | ...
Feb. 22| 2 | | Holiday.|
Feb. 23| 1,600 | ... | 1,100 | ...
Feb. 24| 3 | | Sunday. |
Feb. 25| 1,400 | ... | 600 | ...
Feb. 26| 700 | ... | 650 | ...
Feb. 27| 700 | ... | 2,300 | ...
Feb. 28| 800 | ... | 550 | ...
--------+---------+----------+---------+------------
Mar. 1| 650 | ... | 300 | ...
Mar. 2| 1,000 | ... | 270 | ...
Mar. 3| | Sunday. | |
Mar. 4| 1,200 | ... | 140 | 1.45
Mar. 5| 13,000 | ... | 190 | 1.94
Mar. 6| 18,000 | 2,100 | 160 | 2.03
Mar. 7| 24,000 | 3,500 | 160 | 1.50
Mar. 8| 22,000 | 1,800 | 130 | 1.38
Mar. 9| 24,000 | 3,500 | 130 | 1.37
Mar. 10| | Sunday. | | 1.26
Mar. 11| 18,000 | 6,000 | 120 | 1.24
Mar. 12| 11,000 | 9,000 | 140 | 1.08
Mar. 13| 9,000 | 5,000 | 120 | 0.94
Mar. 14| 5,500 | 3,600 | 90 | 0
Mar. 15| 6,500 | 3,800 | 85 | 0
Mar. 16| 5,000 | 3,500 | 100 | 1.26
Mar. 17| | Sunday. | | 1.52
Mar. 18| 9,000 | 1,900 | 85 | 1.75
Mar. 19| 7,000 | 700 | 65 | 1.57
Mar. 20| 4,800 | 1,500 | 60 | 1.31
Mar. 21| 8,500 | 1,500 | 70 | 1.38
Mar. 22| 7,500 | 1,100 | 35 | 1.57
Mar. 23| 7,500 | 470 | 55 | 1.68
Mar. 24| | Sunday. | | 1.52
Mar. 25|Scraped, 1.03 in. of sand removed.
Mar. 27| 2,200 | 480 | 60 | 1.08
Mar. 28| 1,300 | 250 | 80 | 1.00
Mar. 29| 700 | 240 | 65 | 0
Mar. 30|{Shut down to fill coagulant basin.
|{ 310 | ... | ... | 0
Mar. 31| | Sunday. | | 0
--------+---------+----------+---------+------------
Apr. 1| 600 | 1,000 | 43 | 0
Apr. 2| 270 | Lost. | 35 | 0
Apr. 3| 460 | Apr. | 41 | 0
Apr. 4| 280 | 550 | 27 | 0
Apr. 5| 450 | 1,000 | 60 | 0
Apr. 6| 320 | 50 | 35 | 0
Apr. 7| Sunday.| 0 | |
Apr. 8| 330 | 650 | 22 | 0
Apr. 9| 140 | 750 | 21 | 0
Apr. 10| 750 | 5,000 | 29 | 0
Apr. 11| 4,000 | 550 | 25 | 1.11
Apr. 12| 14,000 | 2,200 | 17 | 1.15
Apr. 13| 13,000 | 3,900 | 25 | 1.14
Apr. 14| | Sunday. | | 1.17
Apr. 15| 7,060 | 2,200 | 19 | 1.09
Apr. 16| 3,600 | 900 | 22 | 1.08
Apr. 17| 1,600 | 1,100 | 12 | 0
Apr. 18| 1,810 | 1,870 | 14 | 0
Apr. 19| 790 | 910 | 14 | 0
Apr. 20| 540 | 480 | 15 | 0
Apr. 21| | Sunday. | | ...
Apr. 22| 235 | 420 | 21 | 0
Apr. 23| 170 | 420 | 8 | 0
Apr. 24| 150 | 250 | 17 | 0
Apr. 25| 700 | 260 | 19 | 0
Apr. 26| 1,200 | 320 | 80 | 0
Apr. 27| 1,700 | 1,500 | 70 | 0
Apr. 28| | Sunday. | | 0
Apr. 29| 600 | 1,400 | 19 | 0
Apr. 30| 550 | 1,200 | 14 | 0
--------+---------+----------+---------+------------
May 1| 500 | 1,300 | 20 | 0
May 2| 500 | 850 | 16 | 0
May 3| 280 | 650 | 34 | 0
May 4| 400 | 550 | 24 | 0
May 5| | Sunday. | | 0
May 6| 390 | 460 | 80 | 0
May 7| 190 | ... | 18 | 0
May 8| ... | ... | ... | 0
May 9| 390 | 1,100 | 14 | 0
May 10| 300 | 500 | 21 | 0
May 11| 390 | 650 | 16 | 0
May 12| | Sunday. | | 0
May 13| 600 | 470 | 27 | 0
May 14| 500 | 550 | 25 | 0
May 15| 500 | 900 | 23 | 0
May 16| 290 | 2,500 | 25 | 0
May 17| 260 | 2,000 | 16 | 0
May 18| 190 | 600 | 19 | 0
May 19| | Sunday. | | 0
May 20| 260 | 450 | 15 | 0
May 21| 260 | 330 | 14 | 0
May 22| 280 | 390 | 22 | 0
May 23| 130 | 240 | 19 | 0
May 24| 170 | 240 | 30 | 0
May 25| 340 | 400 | 41 | 0
May 26| | Sunday. | | 0
May 27| Shut down to scrape sand filter;
| 1.09 in. of sand removed. Cleaning
May 28| coagulant basin and treating coagulant
| basin with 1:2,000,000
May 29| solution of copper sulphate.
May 30| | Holiday. | | 0
May 31| 380 | 18,000 | 150 | 0
--------+---------+----------+---------+------------
June 1| 900 | 7,000 | 150 | 0
June 2| | Sunday. | | 0
June 3| 550 | 8,000 | 130 | 0
June 4| 6,500 | 7,500 | 140 | 0
June 5| 3,200 | 3,600 | 110 | 0
June 6| 1,500 | 800 | 60 | 1.17
June 7| 2,100 | 1,500 | 90 | 1.18
June 8| 660 | 1,000 | 60 | 0
June 9| | Sunday. | | 0
June 10| 240 | 400 | 32 | 0
June 11| 280 | 300 | 31 | 0
June 12| 330 | ... | 28 | 0
June 13| 480 | 480 | 39 | 0
June 14| 440 | 550 | 32 | 0
June 15| 420 | 450 | 27 | 0
June 16| | Sunday. | | 0
June 17| 340 | 750 | 14 | 0
June 18| 440 | 750 | 21 | 0
June 19| 500 | 460 | 35 | 0
June 20| 330 | 440 | 88 | 0
June 21| 170 | 370 | 23 | 0
June 22| 100 | 300 | 17 | 0
June 23| | Sunday. | | 0
June 24| 1,700 | 350 | 22 | 1.59
June 25| 400 | 250 | 16 | 1.55
June 26| 750 | 330 | ... | 0
June 27| ... | 1,400 | ... | 0
June 28| ... | 1,400 | 120 | 0
June 29| 220 | 300 | ... | 0
June 30| | Sunday. | | 0
--------+---------+----------+---------+------------
July 1| 400 | 600 | 85 | 0
July 2| 180 | 1,000 | 50 | 0
July 3| 350 | 310 | 21 | 0
July 4| | Holiday. | |
July 5| 550 | 400 | 41 | 0
July 6| 250 | 280 | 22 | 0
July 7| | Sunday. | | 0
July 8| 220 | 260 | 27 | 0
July 9| 50 | 40 | 19 | 0
July 10| Lost. | Lost. | Lost. | 0
July 11| 150 | 50 | 8 | 1.27
July 12| 300 | 200 | 13 | 1.27
July 13| 220 | 160 | 17 | 1.27
July 14| | Sunday. | | 1.27
July 15| 375 | 150 | | 1.27
July 16| Lost. | 50 | Lost. | 1.36
July 17| 270 | 60 | 3 | 1.26
July 18| 1,675 | 70 | | 1.17
July 19| 450 | 700 | 11 | 0
July 20| 300 | 720 | 8 | 0
July 21| | Sunday. | | 0
July 22| 1,400 | 560 | 14 | 1.17
July 23| 3,700 | 490 | 40 | 1.25
July 24| 770 | 110 | 80 | 1.27
July 25| 250 | 80 | 5 | 1.22
July 26| 140 | 40 | 4 | 0
July 27| 300 | 130 | 21 | 0
July 28| | Sunday. | | 0
July 29| 470 | 290 | 100 | 0
July 30| Lost. | Lost. | Lost. | 0
July 31| July | July | July | 0
--------+---------+----------+---------+------------
Aug. 1| Lost. | Lost. | Lost. | 0
Aug. 2| 130 | 140 | 4 | 0
Aug. 3| 120 | 180 | 6 | 0
Aug. 4| | Sunday. | |
Aug. 5| 230 | 100 | 44 | 0
Aug. 6| 85 | 470 | ... | 0
Aug. 7| 200 | 450 | ... | 0
Aug. 8| 100 | 180 | 45 | 0
Aug. 9| 75 | 80 | 16 | 0
Aug. 10| 60 | 90 | 11 | 0
Aug. 11| | Sunday. | |
Aug. 12| 620 | 260 | 16 | 1.45
Aug. 13| 820 | 520 | 10 | 1.38
Aug. 14| 850 | 120 | 26 | 1.22
Aug. 15| 150 | 260 | 6 | 1.17
Aug. 16| 270 | 340 | 17 | 0
Aug. 17| 340 | 200 | 13 | 0
Aug. 18| | Sunday. | |
Aug. 19| 180 | 220 | 17 | 0
Aug. 20| 210 | 180 | 16 | 0
Aug. 21| 1,300 | 650 | 8 | 0
Aug. 22| 3,800 | 360 | 6 | 0
Aug. 23| 2,500 | 700 | 10 | 0
Aug. 24| 3,900 | 630 | 12 | 0
Aug. 25| | Sunday. | |
Aug. 26| 700 | 310 | 16 | 0
Aug. 27| 470 | 250 | 12 | 0
Aug. 28| 500 | 160 | 18 | 0
Aug. 29| 360 | 110 | 9 | 0
Aug. 30| 320 | 310 | 14 | 0
Aug. 31| 200 | 100 | ... | 0
--------+---------+----------+---------+------------
Sept. 5| 360 | 950 | ... | 1.04
Sept. 6| 15,000 | 1,500 | 190 | 1.35
Sept. 7| 2,000 | 260 | 100 | 1.20
Sept. 8| | Sunday. | ... | 1.04
Sept. 9| 220 | 180 | 38 | 1.04
Sept. 10| 18,000 | 150 | 29 | 1.06
Sept. 11| 2,700 | 200 | 37 | 1.04
Sept. 12| 1,000 | 125 | 19 | 1.04
Sept. 13| 2,300 | 200 | 72 | 1.20
Sept. 14| 2,400 | 360 | 36 | 1.12
Sept. 15| | Sunday. | | 1.04
Sept. 16| Lost.| Lost. | 38 | 1.04
Sept. 17| 420 | 200 | 38 | 1.07
Sept. 18| 900 | 200 | 17 | 1.07
Sept. 19| 2,000 | 220 | 25 | 1.12
Sept. 20| 4,200 | 320 | 31 | 1.24
Sept. 21| 1,100 | 160 | 19 | 1.33
Sept. 22| | Sunday. | | 1.45
Sept. 23| 2,100 | 190 | 15 | 1.41
Sept. 24| 4,000 | 620 | 13 | 1.33
Sept. 25| 56,000 | 290 | 7 | 1.83
Sept. 26| 1,300 | 950 | 19 | 2.34
Sept. 27| 4,000 | Lost. | 20 | 1.91
Sept. 28| 15,000 | 1,000 | 8 | 1.54
Sept. 29| | Sunday. | | 1.34
Sept. 30| Lost. | Lost. | 46 | 1.35
--------+---------+----------+---------+------------
Oct. 1| 600 | 1,700 | 22 | 1.24
Oct. 2| 4,400 | 550 | 8 | 1.09
Oct. 3| 900 | 330 | 15 | 1.04
Oct. 4| 850 | 250 | 11 | 1.03
Oct. 5| 2,000 | 450 | 25 | 1.04
Oct. 6| | Sunday. | | 1.04
Oct. 7| 1,250 | 2,300 | 42 | 1.04
Oct. 8| 11,000 | 100 | 15 | 1.04
Oct. 9| 2,000 | 1,600 | 7 | 1.04
Oct. 10| 800 | Lost. | 24 | 1.04
Oct. 11| 2,000 | 1,200 | 21 | 0
Oct. 12| 1,200 | 1,200 | 19 | 0
Oct. 13| | Sunday. | | 0
Oct. 14| 1,200 | 830 | 25 | 0
Oct. 15| 900 | Lost. | 105 | 0
Oct. 16| Lost. | 550 | 19 | 0
Oct. 17| 550 | 800 | 21 | 0
Oct. 18| 260 | 350 | 9 | 0
Oct. 19| 750 | 310 | 35 | 0
Oct. 20| | Sunday. | | 0
Oct. 21| 480 | 540 | 35 | 0
Oct. 22| 230 | 440 | 17 | 0
Oct. 23| 250 | 440 | 39 | 0
Oct. 24| 300 | 500 | 60 | 0
Oct. 25| 450 | 410 | 65 | 0
Oct. 26| 450 | 500 | 44 | 0
Oct. 27| | Sunday. | | 0
Oct. 28| 190 | 500 | 50 | 0
Oct. 29| 380 | 60 | 75 | 0
Oct. 30| 450 | 180 | 3 | 0
Oct. 31| 2,300 | 390 | 75 | 0
--------+---------+----------+---------+------------
Nov. 4| ... | ... | ... | 0
Nov. 5| 6,000 | 1,600 | 90 | 1.70
Nov. 6| 5,000 | 3,900 | 6 | 1.70
Nov. 7| 14,000 | 300 | 9 | 1.48
Nov. 8| 1,900 | 230 | 2 | 1.27
Nov. 9| 4,000 | 2,700 | 200 | 0
Nov. 10| | Sunday. | | 0
Nov. 11| 1,900 | 2,000 | 200 | 0
Nov. 12| 7,500 | 2,300 | 160 | 0
Nov. 13| 1,600 | 1,100 | 170 | 0
Nov. 14| 2,700 | 950 | 130 | 0
Nov. 15| 1,800 | 800 | 11 | 0
Nov. 16| 1,100 | 800 | 90 | 0
Nov. 17| | Sunday. | | 0
Nov. 18| 1,600 | 700 | 100 | 0
Nov. 20| 6,500 | 120 | 120 | 0
Nov. 21| 9,900 | 1,000 | 80 | 0
Nov. 22| 10,000 | 3, 200 | 90 | 0
Nov. 23| 18,000 | 2, 400 | 100 | 0
Nov. 24| | Sunday. | | 0
Nov. 25| 50,000 | 2, 100 | 65 | 1.68
Nov. 26| 40,000 | 2, 400 | 95 | 1.76
Nov. 27| 16,000 | 2, 600 | 60 | 1.74
Nov. 28| | Holiday. | | 1.57
Nov. 29| 10,000 | 2, 500 | 65 | 1.50
Nov. 30| 3,800 | 1, 900 | 85 | 0
--------+---------+----------+---------+------------
Dec. 6| Scraped, 1.62 in. of sand removed.
Dec. 8| | Sunday. | | 1.17
Dec. 9| 1,200 | 410 | 10 | 1.17
Dec. 10| 800 | 550 | 150 | 1.17
Dec. 11| 6,500 | 600 | 130 | 1.52
Dec. 12| 48,000 | 500 | 130 | 1.99
Dec. 13| 42,000 | 500 | 120 | 2.06
Dec. 14| 49,000 | 750 | 150 | 2.12
Dec. 15| | Sunday. | | 1.69
Dec. 16| 19,000 | 900 | 20 | 1.28
Dec. 17| 21,000 | 400 | 170 | 1.17
Dec. 18| 6,500 | 7,000 | 350 | 1.17
Dec. 19| Lost. | Lost. | Lost. | 1.17
Dec. 20| Dec. | Dec. | Dec. | 1.17
Dec. 21| Dec. | Dec. | Dec. | 1.17
Dec. 22| | Sunday. | | 1.17
Dec. 23| 1,400 | 1,300 | 220 | 1.17
Dec. 24| 9,000 | 1,000 | 140 | 1.49
Dec. 25| | Holiday. | | 2.43
Dec. 26| 51,000 | 1,000 | 39 | 2.15
Dec. 27| 55,000 | 1,600 | 70 | 1.91
Dec. 28| 10,000 | 1,000 | 80 | 1.50
Dec. 29| | Sunday. | | 1.21
Dec. 30| 4,400 | 700 | 80 | 1.17
Dec. 31| 14,000 | 1,200 | 65 | 1.17
--------+---------+----------+---------+------------
1908.
--------+---------+----------+---------+------------
Jan. 1| | Holiday. | | 1.17
Jan. 2| 4,400 | 700 | 19 | 1.17
Jan. 3| 3,100 | 1,000 | 13 | 1.17
Jan. 4| 2,400 | 550 | 19 | 1.17
Jan. 5| | Sunday. | | 1.17
Jan. 6| 600 | 230 | 18 | 1.17
Jan. 7| 1,100 | 370 | 12 | 1.17
Jan. 8| 1,900 | 1,100 | 20 | 1.17
Jan. 9| 13,000 | 1,200 | 22 | 1.21
Jan. 10| 10,000 | 700 | 16 | 1.17
Jan. 11| 16,000 | 1,200 | 11 | 1.17
Jan. 12| | Sunday. | | 1.17
Jan. 13| 8,500 | 90 | 6 | 1.27
Jan. 14| 16,000 | 150 | 23 | 1.56
Jan. 15| 24,000 | 1,100 | 19 | 1.92
Jan. 16| 28,000 | 1,000 | 14 | 2.10
Jan. 17| 65,000 | 490 | 23 | 1.91
Jan. 18| 7,000 | 1,600 | 14 | 1.66
Jan. 19| | Sunday. | | 1.50
Jan. 21| Scrape, 1.45 in. of sand removed.
Jan. 23| ... | ... | ... | 1.17
Jan. 24| 2,300 | 550 | 55 | 1.17
Jan. 25| 1,100 | 850 | 95 | 0
Jan. 26| | Sunday. | | 0
Jan. 27| 300 | 280 | 60 | 0
Jan. 28| 1,200 | 700 | 70 | 0
Jan. 29| 1,000 | 900 | 75 | 0
Jan. 30| 1,400 | 650 | 50 | 0
Jan. 31| 1,100 | 600 | 36 | 0
--------+---------+----------+---------+------------
Feb. 1| 750 | 50 | 25 | 0
Feb. 2| | Sunday. | | 0
Feb. 3| 1,300 | 220 | 16 | 0
Feb. 4| 600 | 370 | 10 | 0
Feb. 5| 750 | 700 | 21 | 0
Feb. 6| 2,000 | 650 | 4 | 0
Feb. 7| ... | 410 | 26 | 0
Feb. 8| 900 | 160 | 42 | 0
Feb. 9| Sunday. | 0
Feb. 10| 850 | 450 | 18 | 0
Feb. 11| 1,000 | 600 | 26 | 0
Feb. 12| 750 | 350 | 16 | 0
Feb. 13| 700 | 120 | 10 | 0
Feb. 14| 1,200 | 950 | 43 | 0
Feb. 15| 5,500 | 1,000 | 23 | 0
Feb. 16| | Sunday. | | 0
Feb. 17| 33,000 | 6,100 | 36 | 0
Feb. 18| ... | 2,000 | 11 | 0
Feb. 19| 28,000 | 9,000 | 120 | 0
Feb. 20| 22,000 | 8,500 | 190 | 0
Feb. 29| ... | ... | ... | 0
--------+---------+----------+---------+------------
Mar. 1| | Sunday. | | 0
Mar. 2| 8,000 | 4,400 | 50 | 0
Mar. 3| 11,000 | 2,100 | 26 | 0
Mar. 4| 6,000 | 4,700 | 7 | 0
Mar. 5| 4,400 | 10,000 | 36 | 0
Mar. 6| 7,000 | 7,400 | 50 | 0
Mar. 7| 9,500 | 6,500 | 28 | 0
Mar. 8| | Sunday. | | 0
Mar. 9| 11,000 | 4,800 | 25 | 0
Mar. 10| 8,500 | 1,200 | 23 | 0
Mar. 11| 6,500 | 2,400 | 20 | 0
Mar. 12| 5,900 | 1,500 | 11 | 0
Mar. 13| 1,900 | 1,100 | 12 | 0
Mar. 14| 1,800 | 700 | 6 | 0
Mar. 15| | Sunday. | | 0
Mar. 16| 1,400 | 700 | 8 | 0
Mar. 17| 900 | 800 | 11 | 0
Mar. 18| 1,000 | 650 | 8 | 0
Mar. 19| ... | 600 | 18 | 0
Mar. 20| 1,300 | 750 | 20 | 0
Mar. 21| 800 | 480 | 18 | 0
Mar. 22| | Sunday. | | 0
Mar. 23| 4,600 | 440 | 19 | 0
Mar. 24| 2,500 | 1,200 | 10 | 0
Mar. 25| 1,600 | 650 | 20 | 0
Mar. 26| 550 | 410 | 7 | 0
Mar. 27| 900 | 900 | 29 | 0
Mar. 28| 650 | 250 | 42 | 0
Mar. 29| | Sunday. | | 0
Mar. 30| 500 | 650 | 28 | 0
Mar. 31| 750 | 290 | 30 | 0
--------+---------+----------+---------+------------
Apr. 1| 750 | 390 | 32 | 0
Apr. 2| 1,100 | 280 | 47 | 0
Apr. 3| 1,500 | 550 | 70 | 0
Apr. 4| 700 | 380 | 4 | 0
Apr. 5| | Sunday. | | 0
Apr. 6| 440 | 150 | 4 | 0
Apr. 7| 650 | 270 | 42 | 0
Apr. 8| 550 | 210 | 65 | 0
Apr. 9| 390 | 160 | 95 | 0
Apr. 10| 500 | 130 | 130 | 0
Apr. 11| 430 | 145 | 100 | 0
Apr. 12| | Sunday. | | 0
Apr. 13| 490 | 160 | 80 | 0
Apr. 14| 550 | 170 | 90 | 0
Apr. 15| 420 | 160 | 12 | 0
Apr. 16| 360 | 130 | 90 | 0
Apr. 21| Scraped, 0.12 in. of sand removed.
Apr. 23| 140 | 140 | ... | 0
Apr. 24| 200 | Lost. | 150 | 0
Apr. 25| 85 | 550 | 45 | 0
Apr. 26| | Sunday. | | 0
Apr. 27| 95 | 850 | 50 | 0
Apr. 28| 70 | 220 | 48 | 0
Apr. 29| 110 | 210 | 95 | 0
Apr. 30| 70 | 140 | 29 | 0
--------+---------+----------+---------+------------
May 1| 130 | 210 | 65 | 0
May 2| 140 | 140 | 55 | 0
May 3| | Sunday. | | 0
May 4| 85 | 210 | 75 | 0
May 5| 130 | 150 | 48 | 0
May 6| 230 | 430 | 50 | 0
May 7| 160 | 90 | 40 | 0
May 8| 375 | 425 | 7 | 0
May 9| 1,209 | 180 | 6 | 0
May 10| | Sunday. | | 0
May 11| 2,800 | 150 | 12 | 0
May 12| 2,900 | 225 | 26 | 0
May 13| 1,800 | 450 | 53 | 0
May 14| 2,700 | 550 | 10 | 0
May 15| 950 | 300 | 65 | 0
May 16| 800 | 250 | 49 | 0
May 17| | Sunday. | | 0
May 18| 700 | 1,700 | 80 | 0
May 19| 375 | 950 | 53 | 0
May 20| 425 | 700 | 46 | 0
May 21| 300 | 600 | 6 | 0
May 22| 950 | 230 | 17 | 0
May 23| 2,400 | 32 | 28 | 0
May 24| | Sunday. | | 0
May 25| 1,100 | 850 | 9 | 0
May 26| 3,200 | 150 | 17 | 0
May 27| 1,450 | 175 | 8 | 0
May 28| 1,000 | 132 | 7 | 0
May 29| 1,100 | 230 | 8 | 0
May 30| | Holiday. | | 0
May 31| | Sunday. | | 0
--------+---------+----------+---------+------------
June 1| ... | ... | ... | 0
June 2| ... | ... | ... | 0
June 3| ... | ... | ... | 0
June 4| ... | ... | ... | 0
June 5| ... | ... | ... | 0
June 6| ... | ... | ... | 0
June 7| ... | ... | ... | 0
June 8| ... | ... | ... | 0
June 9| ... | ... | ... | 0
June 10| ... | ... | ... | 0
June 11| ... | ... | ... | 0
June 12| ... | ... | ... | 0
June 13| ... | ... | ... | 0
June 14| ... | ... | ... | 0
June 15| ... | ... | ... | 0
June 16| ... | ... | ... | 0
June 17| ... | ... | ... | 0
June 18| ... | ... | ... | 0
June 19| ... | ... | ... | 0
June 20| ... | ... | ... | 0
June 21| ... | ... | ... | 0
June 22| ... | ... | ... | 0
June 23| ... | ... | ... | 0
June 26| ... | ... | ... | 0
June 27| ... | ... | ... | 0
June 28| ... | ... | ... | 0
June 29| ... | ... | ... | 0
June 30| ... | ... | ... | 0
--------+---------+----------+---------+------------
July 1| 80 | 75 | 3 | 0
July 2| 290 | 20 | 3 | 0
July 3| 350 | 140 | 4 | 0
July 4| | Holiday. | | 0
July 5| | Sunday. | | 0
July 6| 300 | 52 | 4 | 0
July 7| 110 | 35 | 2 | 0
July 8| 85 | 105 | 2 | 0
July 9| 85 | 80 | 3 | 0
July 10| 300 | 65 | 1 | 0
July 11| 145 | 95 | 11 | 0
July 12| | Sunday. | | 0
July 13| 115 | 105 | 7 | 0
July 14| 800 | 34 | 1 | 0
July 15| 180 | 165 | 3 | 0
July 16| 100 | 95 | 2 | 0
July 17| 65 | 65 | 1 | 0
July 18| 38 | 200 | 24 | 0
July 19| | Sunday. | | 0
July 20| 95 | 31 | 1 | 0
July 21| 70 | 100 | 2 | 0
July 22| 450 | 13 | 4 | 0
July 23| 650 | 325 | 4 | 0
July 24| 1,650 | 325 | ... | 0
July 25| 2,600 | 55 | 2 | 0
July 26| | Sunday. | | 0
July 27| 35,000 | 1,200 | 6 | 0
July 28| 1,200 | 675 | 6 | 0
July 29| 2,000 | 270 | 11 | 0
July 30| 800 | 190 | 2 | 0
July 31| 1,000 | 310 | 6 | 0
========+=========+==========+=========+============
~Table 20--Summary of Results of Experimental Filters.~
==================+========+========+========+=========+=========+========
Filter number.....| 1 | 2 | 3 | 4 | 5 | 6
| | | | | |
Number of runs....| 3 | 6 | 11 | 12 | 25 | 28
------------------+--------+--------+--------+---------+---------+--------
Rate, million gallons per acre per day:
Maximum.......| 1.35 | 3.95 | 7.96 | 12.60 | 37.5 | 118.9
Minimum.......| 0.62 | 2.30 | 3.73 | 5.77 | 6.68 | 7.1
Average.......| 1.06 | 3.26 | 6.69 | 10.17 | 26.1 | 38.54
------------------+--------+--------+--------+---------+---------+--------
Length of run, in days:
Maximum.......| 233.5 | 150.5 | 75.2 | 90.9 | 48.71 | 39.83
Minimum.......| 181.7 | 42.0 | 14.5 | 10.1 | 0.67 | 0.62
Average.......| 206.4 | 109.6 | 48.89 | 40.5 | 14.41 | 12.61
------------------+--------+--------+--------+---------+---------+--------
Million gallons filtered per acre per run:
Maximum.......| 242.61 | 484.46 | 534.67 | 960.72 |1,463.35 |1,022.27
Minimum.......| 202.60 | 135.66 | 93.79 | 92.57 | 19.53 | 53.32
Average.......| 218.58 | 302.82 | 326.76 | 417.23 | 374.14 | 361.92
------------------+--------+--------+--------+---------+---------+--------
Cubic yards of sand removed per acre at end of each run:
Maximum.......| 269 | 269 | 672 |1,612 |2,420 |3,360
Minimum.......| 269 | 134 | 101 | 134 | 134 | 101
Average.......| 269 | 213 | 272 | 392 | 583 | 635
------------------+--------+--------+--------+---------+---------+--------
Cubic yards of | | | | | |
sand removed | | | | | |
per acre per | | | | | |
million gallons | | | | | |
filtered........| 1.23 | 0.70 | 0.83 | 0.94 | 1.55 | 1.72
------------------+--------+--------+--------+---------+---------+--------
Average initial | | | | | |
loss of head....| 0.07 | 0.19 | 0.51 | 0.78 | 3.88 | 5.38
------------------+--------+--------+--------+---------+---------+--------
Turbidity, influent:
Maximum.......| 120 | 120 | 120 | 120 | 90 | 100
Minimum.......| 2 | 2 | 2 | 2 | 2 | 2
Average.......| 20 | 20 | 21 | 22 | 18 | 19
------------------+--------+--------+--------+---------+---------+--------
Turbidity, effluent:
Maximum.......| 11 | 13 | 17 | 18 | 30 | 30
Minimum.......| 0 | 0 | 0 | 0 | 0 | 0
Average.......| 1 | 1 | 2 | 2 | 4 | 3
------------------+--------+--------+--------+---------+---------+--------
Percentage | | | | | |
reduction | 95.0 | 95.0 | 90.5 | 90.9 | 77.8 | 84.3
------------------+--------+--------+--------+---------+---------+--------
Bacteria, influent:
Maximum.......|180,000 |180,000 |180,000 | 110,000 | 180,000 | 37,500
Minimum.......| 22 | 20 | 22 | 20 | 25 | 24
Average.......| 4,800 | 5,100 | 4,500 | 4,200 | 6,900 | 5,900
------------------+--------+--------+--------+---------+---------+--------
Bacteria, effluent:
Maximum.......| 4,000 | 1,300 | 3,200 | 5,400 | 12,800 | 2,400
Minimum.......| 2 | 3 | 1 | 1 | 2 | 2
Average.......| 160 | 85 | 110 | 120 | 190 | 180
------------------+--------+--------+--------+---------+---------+--------
Percentage, | | | | | |
Reduction.......| 96.7 | 98.3 | 97.6 | 97.3 | 97.3 | 97.0
------------------+--------+--------+--------+---------+---------+--------
Number of samples examined for _bacillus coli_ in influent:
10 c.c........| 549 | 478 | 476 | 436 | 325 | 336
1 c.c........| 560 | 492 | 486 | 445 | 335 | 342
0.1 c.c......| 525 | 459 | 452 | 413 | 318 | 317
0.01 c.c.....| 511 | 443 | 439 | 405 | 308 | 304
0.001 c.c....| 500 | 434 | 429 | 394 | 299 | 294
------------------+--------+--------+--------+---------+---------+--------
Number of samples examined for _bacillus coli_ in effluent:
10 c.c........| 512 | 452 | 454 | 404 | 296 | 309
1 c.c........| 513 | 454 | 457 | 406 | 299 | 311
0.1 c.c......| 480 | 419 | 426 | 383 | 271 | 286
0.01 c.c.....| 478 | 406 | 410 | 367 | 261 | 276
0.001 c.c....| 478 | 406 | 410 | 367 | 261 | 276
------------------+--------+--------+--------+---------+---------+--------
Number samples positive, influent:
10 c.c........| 226 | 211 | 201 | 258 | 136 | 152
1 c.c........| 127 | 123 | 116 | 108 | 81 | 93
0.1 c.c......| 55 | 59 | 54 | 51 | 43 | 42
0.01 c.c.....| 26 | 34 | 33 | 33 | 27 | 25
0.001 c.c....| 6 | 6 | 5 | 6 | 3 | 3
------------------+--------+--------+--------+---------+---------+--------
Number samples positive, effluent:
10 c.c........| 100 | 109 | 134 | 98 | 94 | 106
1 c.c........| 51 | 61 | 55 | 56 | 46 | 50
0.1 c.c......| 9 | 13 | 16 | 16 | 4 | 13
0.01 c.c.....| 0 | 0 | 0 | 0 | 0 | 0
0.001 c.c....| 0 | 0 | 0 | 0 | 0 | 0
------------------+--------+--------+--------+---------+---------+--------
Percentage of samples showing _bacillus coli_ in influent:
10 c.c........| 41.2 | 44.2 | 42.2 | 59.2 | 41.9 | 45.2
1 c.c........| 22.7 | 25.0 | 23.9 | 24.3 | 24.2 | 27.2
0.1 c.c......| 10.5 | 12.8 | 11.9 | 12.3 | 13.5 | 13.2
0.01 c.c.....| 5.1 | 7.7 | 7.5 | 8.2 | 8.8 | 8.2
0.001 c.c....| 1.2 | 1.4 | 1.2 | 1.5 | 1.0 | 1.0
------------------+--------+--------+--------+---------+---------+--------
Percentage of samples showing _bacillus coli_ in effluent:
10 c.c........| 19.5 | 24.1 | 29.5 | 24.2 | 31.7 | 34.3
1 c.c........| 10.0 | 13.4 | 12.0 | 13.8 | 15.4 | 16.1
0.1 c.c......| 1.9 | 3.1 | 3.8 | 4.2 | 1.5 | 4.5
0.01 c.c.....| 0 | 0 | 0 | 0 | 0 | 0
0.001 c.c....| 0 | 0 | 0 | 0 | 0 | 0
------------------+--------+--------+--------+---------+---------+--------
Cost per million | | | | | |
gallons for | | | | | |
sand handling.....| $0.43 | $0.25 | $0.29 | $0.33 | $0.54 | $0.60
------------------+--------+--------+--------+---------+---------+--------
Interest charges | | | | | |
at 3%...........| 6.85 | 2.25 | 1.12 | 0.73 | 0.32 | 0.22
------------------+--------+--------+--------+---------+---------+--------
Total.........| 7.28 | 2.50 | 1.41 | 1.06 | 0.86 | .82
==================+========+========+========+=========+=========+=========
_Coli_ tests presumptive.
DISCUSSION
~Allen Hazen, M. Am. Soc. C. E.~ (by letter).--This paper contains a
most interesting and instructive record of the actual operation of a
large filter plant, and also a record of a number of experiments.
The author has described some useful arrangements for improving the
efficiency or reducing the cost.
The utility of raking, as an intermediate treatment between
scrapings, seems to have been clearly demonstrated. Its practical
effect is to allow a greater quantity of water to be passed between
scrapings, thereby saturating--if the term may be used--the surface
layer with clay and other fine matter before removing it, instead of
taking it off when only a thin surface layer of it has been thus
saturated.
The large proportion of the total purification that takes place in
passing through three reservoirs successively, holding in the
aggregate a quantity of water equal to about 7 days' use, is very
striking. Taking all the records, the percentage remaining after
passing through these reservoirs, is as follows:
Sediment for the year, 1909-1910, Table 2....................17%
Turbidities, 5-year average, Table 3.........................25%
Bacteria, 5-year average, Table 4............................24%
Bacteria, selected winter months with high
numbers in the raw water...................................20%
Bacteria, selected summer months with high
numbers in the raw water................................... 2.5%
There is considerable seasonal fluctuation in the results of
settling and filtering, as is shown in Table 21.
~Table 21--Average Removal of Turbidity and Bacteria by
Washington Filters for Whole Period, Arranged by Seasons~.
===========================+========+========+========+========+========
| Winter.| Spring.| Summer.| Fall. | Year.
----------------+----------+--------+--------+--------+--------+--------
Turbidity, in | raw | 135 | 96 | 144 | 42 | 105
parts per | settled | 33 | 28 | 27 | 15 | 26
million: | filtered | 4 | 3 | 1 | 0.5 | 2
----------------+----------+--------+--------+--------+--------+--------
Percentage | settling | 24 | 29 | 19 | 36 | 25
left from: | filtering| 12 | 10 | 4 | 3 | 8
| both | 3 | 1 | 0.3 | 1 | 2
----------------+----------+--------+--------+--------+--------+--------
Bacteria per | raw | 16,600 | 4,150 | 4,100 | 1,960 | 6,700
cubic | settled | 6,300 | 980 | 160 | 270 | 1,940
centimeter: | filtered | 149 | 29 | 18 | 22 | 54
----------------+----------+--------+--------+--------+--------+--------
Percentage | settling | 38 | 24 | 4 | 14 | 29
left from: | filtering| 2.4 | 3.0 | 11.2 | 8.2 | 2.8
| both | 0.90 | 0.79 | 0.44 | 1.12 | 0.81
================+==========+========+========+========+========+========
The fluctuation in the efficiency of the plant as a whole by seasons
is greater with the turbidity than with the bacteria. During the
winter the effluent contains 3% of the turbidity of the raw water,
and in summer only 0.3 per cent. Most of this difference is
represented by the increased efficiency of the filters in summer,
and only a little of it by the increased efficiency of settling.
With bacteria, on the other hand, the seasonal fluctuation of the
plant as a whole is comparatively small, but the settling and
storage processes are much more efficient in summer than in winter,
the filters being apparently less efficient. The writer believes
that they are only apparently less efficient, and not really so, the
explanation being that some bacteria always grow in the under-drains
and lower parts of the filter, and are washed away by the effluent.
The average number of bacteria in summer in the settled water is 160
per cu. cm. and in the filtered water 18. These are very low
numbers. It is the writer's view that nearly all of these 18
represent under-drain bacteria, and practically bear no relation to
those in the applied water, and, if this view is correct, the number
of bacteria actually passing through the various processes is at all
times less than the figures indicate. In the warmer part of the year
the difference is a wide one, and the hygienic efficiency of the
process is much greater than is indicated by the gross numbers of
bacteria.
The reduction of the typhoid death rate has not been as great with
the change in water supply as was the case at Lawrence, Albany, and
other cities, apparently because the Potomac water before it was
filtered was not the cause of a large part of the typhoid fever.
The sewage pollution of the Potomac is much less than that of the
Merrimac and the Hudson, and it is perhaps not surprising that this
relatively small amount of pollution was less potent in causing
typhoid fever than the greater pollution of rivers draining more
densely populated areas.
The method of replacing the washed sand hydraulically seems to have
worked better than could have been reasonably anticipated, and the
writer believes that this was due, in part, to the excellent method
of manipulation described in the paper. It is his feeling, however,
that part of the success is attributable to the very low uniformity
coefficient of the sand. In other words, the sand grains are nearly
all of the same size, due to the character of the stock from which
the filter sand was prepared; and, therefore, there is much less
opportunity for separation of the sand according to grain sizes than
there would be with the filter sand which has been available in most
other cases. Filter sand with a uniformity coefficient as low as
that obtained at Washington has been rarely available for the
construction of sand filters, and while the method of hydraulic
return should certainly be considered, it will not be safe to assume
that equally favorable results may be obtained with it with sands of
high uniformity coefficients until actual favorable experience is
obtained.
The writer believes that in calculating the cost of the water used
in the plant itself the price chosen by the author, covering only
the actual operating expenses of pumping and filtering, is too low.
The capacity of the whole Washington Aqueduct system is reduced by
whatever quantity is used in this way, and, in calculating the cost
of sand handling, the value of the water used should be calculated
on a basis which will cover the whole cost of the water, including
all capital charges, depreciation, operating expenses, and all costs
of every description. On this basis the water used in the
sand-handling operations would probably be worth five or more times
the sum mentioned by the author.
The cost of operation of the plant has come within the estimates
made in advance, and has certainly been most reasonable. The cost of
filter operations has averaged only about 50 cents per million
gallons, and is so low that it is obvious that the savings which may
be made by introducing further labor-saving appliances would be
relatively small. It will be remembered that ten or fifteen years
ago the cost of operating such filters under American conditions was
commonly from $2 to $5 per million gallons.
The experiments represented by Tables 17 to 19, inclusive, serve to
show that preliminary filtration, or multiple filtration, or any
system of mechanical separation is incapable of entirely removing
the finer clay particles which cause the residual turbidity in the
effluent. They also show that this turbidity may be easily and
certainly removed by the application of coagulant to the raw water
during the occasional periods when its character is such as to
require it.
These general propositions were understood by those responsible for
the original design of the plant, as is shown by the author's
quotations. These experiments, however, were necessary in order to
demonstrate and bring home the conditions to those who thought
differently, and who believed that full purification could be
obtained by filtration alone, or by double filtration, without
recourse to the occasional use of coagulant.
The experiments briefly summarized in Table 20 are of the greatest
interest and importance. Six small filters, otherwise alike and like
the large filters, all received the same raw water and were operated
at different rates to determine the effect of rate on efficiency.
That the experimental results from the filter operating at the same
rate as the large filters were on the whole somewhat inferior to
those from the large filters for approximately the same period, may
be attributed to the fact that the experimental filter was new while
the large filters had been in service for some time and had thereby
gained in efficiency. The greatest difference was in the _coli_
results in Table 20, where it is shown that 24% of the 10-cu. cm.
effluent samples from the experimental filter contained _coli_, in
comparison with only from 1 to 3% of such samples from the main
filters.
The results from the experimental filter operating at a rate of
1,000,000 gal. per acre daily may fairly be excluded, as the
effluent probably contained more under-drain bacteria in proportion
than filters operated at higher rates. The number of bacteria in the
filter operating at a 3,000,000-gal. rate were 1.7% of those in the
applied water; for the filter operating twice as fast, the
percentage was 2.4; and, for the one operating more than ten times
as fast, was only 3.0; thus indicating a surprisingly small increase
in the number of bacteria with increase in rate.
Further and more detailed study by the writer of the unpublished
individual results, briefly summarized in Table 20, confirms the
substantial accuracy of the comparison based on the average figures
as stated in that table.
It must be kept in mind, in considering these results, that the
number of bacteria in each case is made up of two parts, namely,
those coming through the filter--which number is presumably greater
as the rate is greater--and, second, those coming from harmless
growths in the under-drains and lower parts of the filter--the
numbers of which per cubic centimeter are presumably less as the
rate is greater--and these two parts, varying in opposite
directions, may balance each other, as they seem to do in this case,
through a considerable range. It may thus be that the number of
bacteria really passing the filter varies much more with the rate
than is indicated by the gross results.
It is also of interest to note that the sand filter (called a
preliminary filter) in Table 18, filled with the same kind of sand,
when operated at an average rate of 50,000,000 gal. per acre daily
for a year, allowed 18% of the applied bacteria to pass, in
comparison with 3% found in Filter No. 6 of Table 20, operated at an
average rate of 38,000,000 gal. per acre daily.
There was one point of difference in the manipulation: the
preliminary filter was washed by a reversed current of water, as
mechanical filters are washed, while Filter No. 6 was cleaned by
scraping off the surface layer, as is usual with sand filters.
Whether the great difference in bacterial results with a relatively
small difference in rate is to be attributed to this difference in
manipulation the writer will not undertake to state.
If the experimental results of Table 20 indicate correctly the
conditions which obtain in filtering Potomac water, then increasing
the rate of filtration so as to double it, or more than double it,
would make but little difference in the quality of the effluent as
measured by the usual bacterial methods. If the increase in rate
were accompanied by the preliminary filtration of the water, then,
presumably, there would be little change in the quality of the
effluent, and the maintenance of excellent results might be
incorrectly attributed to the influence of the preliminary filter.
It would also seem that the apparatus which is sometimes used for
determining and controlling the rate with more than the ordinary
degree of precision is hardly justified by such experimental results
as those presented by the author.
In contrast to these results may be mentioned those obtained by Mr.
H. W. Clark,[1] for experimental filters operated with Merrimac
River water, at rates ranging from 3,000,000 to 16,000,000 gal. per
acre daily. The results are the average of nearly two years of
experimental work, the period having been nearly coincident with
that covered by the author's experiments, and of many hundreds of
bacterial analyses of each effluent, and form, with the author's
experiments, the most thorough-going studies of the effect of rate
on efficiency that have come to the writer's attention.
Mr. Clark's results are given in Table 22.
~Table 22.~
===========+============+===========+=============+===========+============
| | | | | _B. Coli_
| | | | |in 1 cu.cm.
Effective | | Rate | Bacteria per| |(percentage
size of | | in gallons| cubic | Bacterial |of positive
sand. | Filter No. |acre daily.|centimeter in|efficiency.| tests).
-----------+------------+-----------+-------------+-----------+------------
0.28 | A | 3,000,000 | 48 | 99.1 | 5.0
0.25 | B | 5,000,000 | 85 | 98.4 | 24.0
0.22 | C | 7,500,000 | 105 | 98.1 | 25.0
0.22 | D |10,000,000 | 110 | 98.0 | 25.0
0.22 | E |16,000,000 | 280 | 95.0 | 38.0
===========+============+===========+=============+===========+============
It will be seen that the number of bacteria passing increases
rapidly with the rate, and whether the total number of bacteria is
considered or the _B. coli_ results, the number passing is
approximately in proportion to the rate. In other words, doubling
the rate substantially doubles the number of bacteria in the
effluent.
This is entirely in harmony with all the Lawrence experimental
results extending over a period of 20 years. There have been
occasional apparent exceptions, but, on the whole, experience with
Merrimac River water has uniformly been that more bacteria pass as
the rates are higher.
The theory sometimes advanced, that the efficiency of filtration is
controlled to a certain extent by gelatinous films, and that, as far
as thus controlled, is less dependent on rate, would not seem to be
borne out by these results. The Merrimac River water, carrying large
amounts of organic matter, would certainly seem better adapted to
the formation of such films than the clay-bearing Potomac water,
comparatively free from organic matter; but it is the Potomac water
which seems to show the least influence of rate on efficiency.
[Footnote 1: _Journal_, New England Water-Works Association, Vol.
24, p. 589.]
The experiments show that turbidity passes more freely at the higher
rates with the Potomac water, as has also been found to be the case
with other clay-bearing waters.
In the last lines of Table 20 are given cost per million gallons for
filtering at various rates. There is no discussion of these figures,
and as they differ considerably from those which the writer has been
accustomed to use, the calculation in Table 23, made three years ago
for a particular case, may be of interest.