Historic Pelham: 1921 Report of Inspection of the Pelham Reservoir Water Supply System

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It certainly is difficult to imagine today, but during the late nineteenth and early twentieth centuries, our region received its potable water from the Hutchinson River. The Pelham Reservoir was constructed as part of a series of connected reservoirs intended to store water to meet the region's growing water needs. Recently I have written about the evolution of the facilities developed to meet the ever-growing water needs of the Town of Pelham and the surrounding region. See

Wed., Mar. 11, 2015: Research Regarding the History of the Pelham Reservoir in Today's Willsons Woods Park.

Fri., May 1, 2015: Pelham Manor's Efforts to End Use of the Pelham Reservoir for Drinking Purposes.

Detail of 1910 Map Showing Pelham Reservoir and Filter Beds.

Source: Bromley, George W. & Bromley, Walter S., Untitled

Map Bounded by Town of East Chester, City of New Rochelle,

Pelham Station, Clarefmont Avenue and Central Boulevard

in Atlas Of Westchester County, Vol. One, p. 17

(Philadelphia, PA: G. W. Bromley & Co., 1910).

Today's posting to the Historic Pelham Blog transcribes the entirety of a brief inspection report reflecting inspections of the water purification and delivery systems of the New York Interurban Water Company in late 1921. These systems delivered drinking water to a wide region and included the Pelham Reservoir and its pumping and filter bed systems. The report provides a stark reminder of just how crude these early water purification systems actually were.

"NEW YORK INTERURBAN WATER COMPANY

A reinspection of the public water supply furnished by the New York Interurban Water Company to the city of Mt. Vernon and to the village of Mamaroneck, town of Harrison, and the districts of Orienta and Rye Neck, Westchester county, N. Y., was made by Mr. Alfred Mullikin, a representative of this Department on October 4, 1921. Previous inspections of this supply have been made by this Division in 1909, 1915, and 1920 and the reports thereon published in the Annual Reports of the Department for those years.

Mt. Vernon, a city with a present population estimated at 43,000 is located north and adjacent to New HYork City on the Bronx river. The village of Mamaroneck and the other districts served lie to the northeast of the city and have an estimated population of 9,000. Of the total population, all are served with water from the public water supply. The waterworks are owned and operated by the New York Interurban Water Company under the direction of Mr. H. E. Walbert, superintendent. The water supply of the New York Interurban Water Company is obtained from three sources namely, the Hutchinson river, Tom Paine brook and the Mamaroneck river. The supply from the Hutchinson river consists mainly of the overflow from the New Rochelle reservoirs together with the drainage from the watershed between these reservoirs and the reservoir of the Interurban Company at Pelham. The water from Tom Paine brook is collected in a large reservoir, known as the Mahlstead reservoir, from which it is siphoned to the Pelham reservoir. The water from these 2 sources is then filtered through open slow sand filters. The supply from the Mamaroneck river is collected in a small storage reservoir and then pumped through pressure mechanical filters after coagulation and sedimentation in a preliminary settling basin and after treatment with hypochlorite of lime. The description of these two filter plants will be found on pages 419 and 429, Vol. 2 of the 30th Annual Report of this Department.

After filtration and sterilization, the water passes into a distributing system. The water mains over the entire system are flushed once a year. The average daily water consumption for the month of September was 3,694,554 gallons, of which some 2,377,400 gallons was supplied by the Mamaroneck plant and 1,317,250 gallons by the Pelham plant. Storage is provided by a steel stand pipe.

The Mamaroneck reservoir formed by a timber and stone dam is located about 8 miles east of the center of the city of Mt. Vernon and about 1 mile north of the village of Mamaroneck. Signs are posted to prevent trespassing but the reservoir is not fenced. Monthly inspections are made and copper sulphate is added 3 or 4 times a year to inhibit the growth of algae. Above the reservoir the drainage area of the Mamaroneck river is about 12.8 square miles. The soil is rocky and traversed by a number of highways along which are numerous houses on the watershed. The river receives surface wash from this populated area. It is also said that the supply is subject to direct pollution from time to time from the overflow of sewers carrying sewage from the city of White Plains. The Pelham reservoir is located about 1 1/2 mies east of the center of the city of Mt. Vernon and north of the New York, New Haven and Hartford Railroad. Although signs against trespassing are posted, the reservoir is not fenced. The physical condition of the water was somewhat impaired at the time of the inspection due to the presence of algae growths in the reservoir. Located near the inlet pipe leading from the reservoir to the slow sand filters, a barrel is placed and used in connection with the application of copper sulphate for treatment of the raw water at a rate of 5 pounds per day or approximately 0.46 parts per million. The Peham reservoir is fed by water from the Hutchinson river and the Tom Paine brook. The Hutchinson river has a drainage area of about 2 square miles and receives the overflow from the New Rochelle reservoirs. There are also numerous houses and highways on this watershed which in all probability give rise to pollution of the supply. It was learned that the Hutchinson river receives direct pollution from leaks occurring in a tile sewer laid in Hutchinson boulevard. Tom Paine brook has a drainage area of about 1.9 square miles. The water is collected in two small rip-rapped ponds in the city of New Rochelle and flows to Mahlstead storage reservoir. The watershed receives less pollution than the other sources. It contains some swamp area above the upper pond and is open to the public. Above the upper pond crossing the brook in Wykagyl park, the city of New Rochelle has recently laid sewers constructed of 24-inch cast-iron pipe with leaded joints. The Mahlstead reservoir is rectangular in shape and rip-rapped. Although signs are posted prohibiting trespassing, 5 people were fishing from the banks of the reservoir at the time of the inspection. Although the reservoir is treated with copper sulphate several times a year, the water contained considerable algae. Rules and regulations for the sanitary protection of the public water supply of the city of Mt. Vernon were enacted by this Department in 1907.

The Pelham filter plant is located at the Pelham reservoir, 1 mile east of the city of Mt. Vernon and consists of 3 slow sand filters. With a consumption of 1.3 million gallons of water per day, the filters were operating at a rate of 1.16 million gallons of water per day, the filters are cleaned about every 6 weeks, when 1/2-inch of sand is removed at each cleaning. Two of the filters were being cleaned at the time of the inspection. The filtered water is sterilized with liquid chlorine which is applied by a Wallace and Tiernan manual control solution feed chlorinator having a pulsometer capacity of 45 c.c. At the time of the inspection chlorine was being applied at the rate of 0.8 parts per million. An additional new chlorine apparatus has been installed, having a pulsometer capacity of 39 c.c. This apparatus is held in reserve.

The Mamaroneck filter plant is located about 1 mile north of the village of Mamaroneck and some 200 feet below the impounding Mamaroneck reservoir. The water from this reservoir flows by gravity to a coagulating basin. It is cleaned every three months. From the coagulating basin the water flows through 4 horizontal pressure mechanica filters. With a consumption of 2.38 million gallons of water, the rate of filtration based on a cross-sectional area of 160 square feet each, would be 162 million gallons per acre per day. Every day two of the four filters are washed giving a 48 hour run between washing for each filter. The first filtrate is not wasted. At the time of the inspection some 200 pounds of alum were being applied to the raw water per day, the rate of application is 0.59 grains per gallon which gave a satisfactory floe to the raw water.

The filtered water is sterilized with liquid chlorine at nearly 1.3 parts per million. From the recent inspection if appears that our previous recommendations have been carried out with the exeption that the chlorine cylinder connections have not been arranged so that two cylinders may be kept connected to the apparatus at all times.

The results of the analyses of the filtered and chlorinated water made by the Division of Laboratories and Research and collected at the Pelham plant show nearly 100 per cent removal of turbidity, 50 per cent removal of color, 70 per cent and 53 per cent removal of organic matter as measured by the albuminoid ammonia and oxygen consumed tests respectively. The results of the bacteriological examination show a total bacterial increase of some 92 per cent as indicated by the 20 degree count which is probably due to the fact that one of the filters had just been cleaned prior to the time of the inspection. The results of the analyses of the filtered and chlorinated water collected at the Mamaroneck plant show nearly 100 per cent removal of turbidity, 58 per cent and 47 per cent removal of organic matter as measured by the albuminoid ammonia and oxygen consumed tests respectively. The results of the bacteriological examination show a total bacterial removal of 94 per cent as indicated by the 20 degree count and a removal of 100 per cent of organisms of the B. coli type in all inoculations examined.

In a report upon an inspection of the supply dated December 20, 1921, the following recommendations were made:

1. That as previously recommended the Interurban Water Company maintain at all times a careful supervision over the watersheds tributary to the supply.
2. That adequate pumping machinery be installed at the Westchester avenue sewage pumping station and care be taken to see that no sewers overflow or other sources of pollution continue.
3. That frequent tests of the treated water at both filter plants for excess chlorine be made by the starch iodide method in accordance with the enclosed directions, and the rate of application of the chlorine regulated in accordance with the results of these tests.
4. Taht the water company make careful daily tests of the raw and filtered water with a view to determining the exact quantity of alum and chlorine require at all times and the rate of application of these chemicals be regulated in accordance with the results of these tests and applied continuously.
5. That copper sulphate be properly applied to the Pelham and Mahlstead reservoirs throughout the year under the supervision of a competent expert in order to prevent the occurrence of algae growths in the reservoir.
6. That the present depth of sand on the Pelham filters be increased by the addition of a suitable quality of sand and at no time shouldd the depth be less than 30 inches.
7. That the water company increase the filter capacity of the Mamaroneck filter plant in order that the rate of filtration will not at any time exceed 125,000,000 gallons per acre per day.
8. That the pressure gauges on the filters of the Mamaroneck plant be tested and the filters washed frequently in order that at no time may the loss of head exceed 10 feet, or a difference of 4 pounds on the gauges.
9. That in accordance with the previous report two chlorine cylinders be attached to the chlorine apparatus at all times so that an interval of time will not elapse when gas is not applied to the filtered water when changing cylinders,"

Source: State of New York Forty-Second Annual Report of the State Department of Health For the Year Ending December 31, 1921, Vol. I, pp. 204-06 (Albany, NY: B. Lyon Company, 1922).