Transactions of the American Society of Civil Engineers, vol. LXXII, June, 1911 / Water Purification Plant, Washington, D. C. Results of Operation. - American Society of Civil Engineers; E. D. Hardy

Table 5—Results of Tests for *Bacillus Coli*.
Percentage Positive.
Month.	Great Falls, or Dalecarlia Reservoir Inlet.			Dalecarlia Reservoir Outlet.			Georgetown Reservoir.			McMillan Park Reservoir (applied water).			Filtered water reservoir.		Tap water from various parts of city.
Month.	10 c.c.	1 c.c.	0.1 c.c.	10 c.c.	1 c.c.	0.1 c.c.	10 c.c.	1 c.c.	0.1 c.c.	10 c.c.	1 c.c.	0.1 c.c.	10 c.c.	1 c.c.	10 c.c.	1 c.c.
1906.
January[¹]	55.6	38.9	22.2	69.2	23.1	7.7	56.0	40.0	8.0	55.6	22.2	0	7.2	0	...	...
February	33.3	26.7	6.7	26.1	17.4	8.7	30.4	13.0	4.4	8.3	4.2	0	0	0	...	...
March	50.0	12.5	0	45.5	18.2	0	20.8	8.3	0	18.5	7.4	3.7	0	0	0	0
April	72.2	33.3	16.7	95.5	50.0	4.6	59.1	22.7	4.6	32.0	8.0	0	4.0	0	0	0
May	20.0	8.0	4.0	20.0	12.0	0	7.8	0	0	0	0	0	0	0	0	0
June	57.7	38.5	19.2	40.0	32.0	8.0	50.0	34.6	0	23.1	7.7	3.8	0	0	3.1	0
July	65.0	50.0	5.0	60.0	25.0	10.0	15.0	5.0	5.0	9.5	0	0	4.8	0	...	...
August	84.6	69.2	61.5	88.5	65.4	34.6	80.0	57.7	23.1	63.0	33.3	0	7.4	3.7	11.9	5.1
September	50.0	10.0	0	30.0	10.0	10.0	40.0	10.0	0	32.0	12.0	0	8.0	0	3.1	0
October	60.0	30.0	10.0	55.5	33.3	0	80.0	60.0	20.0	48.1	22.2	3.7	3.7	0	13.0	3.7
November	37.5	0	0	25.0	12.5	12.5	37.5	25.0	0	20.0	12.0	0	8.0	0	0	0
December	55.5	44.5	0	66.7	44.5	22.2	66.7	22.2	0	20.8	8.3	4.2	16.7	8.3	7.5	0
1907.
January	77.8	33.3	22.2	66.7	33.3	0	55.5	55.5	22.2	69.3	34.6	3.8	19.2	11.5	14.0	0
February	37.5	25.0	0	12.5	0	0	37.5	12.5	0	17.4	4.4	0	0	0	2.9	0
March	87.5	50.0	0	75.0	37.5	0	50.0	25.0	0	30.8	7.7	0	0	0	2.1	0
April	44.5	11.1	11.1	66.7	22.2	11.1	77.8	11.1	11.1	46.1	19.2	3.8	3.8	0	3.2	0
May	91.3	65.2	17.4	88.9	33.3	0	87.5	50.0	12.5	23.1	0	0	0	0	1.4	0
June	80.0	68.0	24.0	87.5	62.5	0	66.7	44.5	11.1	40.0	8.0	0	0	0	0	0
July	42.3	30.8	19.2	25.0	12.5	0	22.2	22.2	0	3.8	0	0	0	0	1.4	1.4
August	48.1	29.6	3.7	33.3	16.7	16.7	36.4	18.2	0	14.8	3.7	0	0	0	0	0
September	62.5	54.1	25.0	...	...	...	41.7	33.3	16.7	16.0	4.0	0	4.0	0	1.7	0
October	51.9	40.8	7.4	...	...	...	53.3	40.0	6.7	38.7	25.8	9.7	6.5	0	12.5	2.8
November	80.0	64.0	24.0	...	...	...	72.7	54.5	0	58.6	17.3	3.5	0	0	4.9	0
December	56.0	48.0	16.0	...	...	...	46.2	38.5	7.7	45.2	29.0	0	19.3	3.2	12.9	4.3
1908.
January	46.2	30.8	15.4	50.0	12.5	0	33.3	0	0	22.6	9.7	3.2	3.2	0	1.9	1.9
February	12.5	0	0	25.0	0	0	12.5	0	0	0	0	0	0	0	0	0
March	38.5	19.2	7.7	44.4	11.1	0	11.1	0	0	9.7	0	0	0	0	0	0
April	15.4	7.7	0	0	0	0	0	0	0	6.7	3.3	0	0	0	0	0
May	76.0	52.0	40.0	87.5	50.0	12.5	33.3	22.2	0	45.1	16.2	0	0	0	0	0
June	7.7	0	0	0	0	0	11.1	0	0	0	0	0	0	0	0	0
July	26.9	15.4	11.5	22.2	22.2	0	11.1	0	0	6.4	6.4	0	0	0	0	0
August	46.2	26.9	3.9	44.4	33.3	0	62.5	25.0	12.5	12.9	3.2	0	0	0	1.6	0
September	20.0	8.0	4.0	42.9	28.6	1.4	22.2	11.1	0	16.7	10.0	0	0	0	4.3	0
October	18.4	3.7	0	0	0	0	9.1	0	0	9.7	6.4	3.2	0	0	0	0
November	13.0	0	0	28.6	0	0	11.1	0	0	6.6	0	0	0	0	0	0
December	11.5	7.7	3.8	0	0	0	12.5	0	0	3.2	0	0	0	0	0	0
1909.
January	12.0	8.0	0	30.0	10.0	0	0	0	0	3.2	3.2	0	3.2	0	0	0
February	52.1	47.8	47.8	28.6	14.3	0	37.5	0	0	7.1	3.6	3.6	0	0	3.4	3.4
March	69.4	34.6	3.8	50.0	25.0	0	44.5	11.1	0	32.3	19.4	3.2	6.5	0	2.8	1.4
April	42.3	15.4	3.9	33.3	22.2	11.1	44.4	22.2	11.1	36.6	10.0	0	0	0	0	0
May	88.4	26.1	4.3	50.0	12.5	0	33.3	0	0	12.9	3.2	0	0	0	0	0
June	85.0	60.0	25.0	60.0	40.0	10.0	44.4	33.3	11.1	53.3	20.0	0	0	0	1.4	0
July	34.8	8.7	4.4	...	...	...	33.3	11.1	0	25.8	12.9	0	0	0	0	0
August	50.0	15.4	7.7	...	...	...	40.0	10.0	0	22.6	6.5	3.2	0	0	0	0
September	43.5	21.8	8.7	25.0	25.0	12.5	0	0	0	13.3	3.3	0	0	0	0	0
October	36.4	13.6	0	18.2	0	0	0	0	0	3.2	0	0	0	0	0	0
November	4.5	0	0	10.0	0	0	0	0	0	0	0	0	0	0	0	0
December	38.5	23.1	7.7	36.4	36.4	18.2	33.3	22.2	11.1	29.0	22.6	0	9.7	6.5	7.3	1.5
1910.
January	72.0	48.0	24.0	44.5	33.3	11.1	75.0	25.0	0	61.3	35.5	9.7	5.8	3.2	15.9	3.2
February	47.8	43.5	17.4	63.2	21.1	5.3	40.0	30.0	5.0	32.2	7.1	0	3.6	0	0	0
March	33.3	14.8	0	30.8	11.1	3.7	29.6	22.2	7.4	12.9	3.2	0	0	0	0	0
April	41.7	33.3	20.8	40.0	32.0	16.0	38.5	23.1	15.4	23.3	13.3	0	0	0	0	0
May	47.8	17.4	0	52.0	20.0	0	36.0	16.0	4.0	16.1	12.9	0	0	0	0	0
June	95.5	86.4	31.8	80.8	46.2	19.2	64.0	28.0	8.0	43.3	6.7	0	0	0	1.4	0
Fiscal years:
1905-06	35.2	19.4	9.3	0.0	3.2	5.2	6.4	4.9	1.7	4.3	8.3	.8	.3	1.8	1.3	0
1906-07	61.5	43.6	9.2	7.7	9.2	2.3	1.1	9.8	0.7	2.5	3.0	.4	.5	2.1	5.4	1.0
1907-08	44.6	31.3	3.0	2.3	2.3	3.1	4.4	2.1	4.1	2.2	9.4	.4	.8	0.3	3.1	0.9
1908-09	38.9	20.3	8.4	0.0	5.0	0	7.4	8.5	2.8	6.7	7.1	.8	.8	0	1.2	0.4
1909-10	45.5	26.9	0.1	5.3	4.0	8.8	7.9	9.8	6.2	3.6	0.4	.1	.3	0.8	2.2	0.4

[¹ Presumptive tests.]

Table 6—Summary of Sanitary Chemicals Analyses of Weekly Samples, July 1st, 1909, to June 30th, 1910.
(Results in Parts per Million.)
(A) Maximum.
Reservoirs.	Turbidity[¹]	Ammonia.			Nitrogen as:		Hardness	Alkalinity	Chlorine
Reservoirs.	Turbidity[¹]	Free	Albuminoid	Total	Nitrites	Nitrates	Hardness	Alkalinity	Chlorine
Dalecarlia inlet	2,100	0.034	0.264	0.280	0.0070	0.45	120.0	106.0	5.4
Dalecarlia outlet[²]	200	0.034	0.180	0.206	0.0050	0.70	115.0	105.8	5.7
Georgetown outlet[³]	215	0.030	0.182	0.182	0.0060	0.60	115.0	105.0	4.9
McMillan Park outlet	120	0.028	0.126	0.154	0.0060	0.65	118.0	104.4	4.2
Filtered water	9	0.016	0.078	0.086	0.0010	0.70	119.5	106.3	4.5

Table 6—(*Continued.*)
(B) Minimum.
Reservoirs.	Turbidity[¹]	Ammonia.			Nitrogen as:		Hardness	Alkalinity	Chlorine
Reservoirs.	Turbidity[¹]	Free	Albuminoid	Total	Nitrites	Nitrates	Hardness	Alkalinity	Chlorine
Dalecarlia inlet	7	0.000	0.016	0.016	0.0000	0.00	52.9	39.5	1.0
Dalecarlia outlet[²]	7	0.000	0.040	0.040	0.0000	0.00	54.3	38.2	0.9
Georgetown outlet[³]	7	0.000	0.044	0.044	0.0000	0.00	51.4	40.6	0.7
McMillan Park outlet	2	0.000	0.010	0.010	0.0010	0.00	51.4	38.5	0.2
Filtered water	0	0.000	0.000	0.000	0.0000	0.00	52.9	40.3	0.4

Table 6—(*Continued.*)
(C) Average.
Reservoirs.	Turbidity[¹]	Ammonia.			Nitrogen as:		Hardness	Alkalinity	Chlorine
Reservoirs.	Turbidity[¹]	Free	Albuminoid	Total	Nitrites	Nitrates	Hardness	Alkalinity	Chlorine
Dalecarlia inlet	86	0.006	0.167	0.113	0.0027	0.19	93.2	81.4	2.9
Dalecarlia outlet[²]	30	0.008	0.106	0.114	0.0023	0.18	95.5	79.5	3.4
Georgetown outlet[³]	29	0.005	0.101	0.106	0.0027	0.18	93.4	80.9	2.9
McMillan Park outlet	18	0.004	0.077	0.081	0.0027	0.17	94.0	83.0	2.7
Filtered water	1	0.002	0.027	0.029	0.0000	0.19	94.9	84.0	2.8

[¹ Summary of daily samples of water.]

[² Reservoir out of service from July 1st to September 13th, 1909.]