THE WATER SUPPLY OF-SALEM AND BEVERLY
The cities of Salem and Beverly have for many years past taken their water supply from Wenham Lake, which lies in the towns of Beverly and Wenham. This use dates back to the year 1864, when the legislature granted to the city of Salem the right to use the water of Wenham Pond, with a provision that the pipes supplying Salem should be carried by some convenient route through the town of Beverly, and that Beverly should be entitled to the reasonable use of the water upon paying an equitable compensation therefor. The first actual use of the water in Salem was in 1868, and in 1869 Beverly began making use of the water through the setting of certain hydrants. For a number of years both cities thus drew water from the same mains. An act of the legislature was passed in 1885 granting the town of Beverly the necessary authority to build an independent works, and construction work commenced in 1886. In September, 1887, the town of Beverly stopped drawing water from the Salem pipes and commenced the use of this new system. From that time to the present, the two cities have drawn their supplies independently from Wenham Lake, with independent mains, service reservoirs and pumping stations. They have, in general, been administered separately since 1887, but as the consumption of the two cities has increased and approached the limiting capacity of the source, the cities have acted in conjunction in securing certain additions to this capacity. The drainage area of Wenham Lake is about 2,250 acres, of which about 250 acres is water surface. The storage in the lake, to a depth of 14 feet, which is about the limit of draft with present equipment, is about 900,000,000 gallons, and this could be increased to about 1,200,000,000 gallons by drawing the lake down 20 feet. In the early nineties the probability of a shortage of water was so great that the cities were forced into action. In 1895 a dam was built on Miles River, forming what is called the Longham Pond. The crest of the dam is at an elevation 5 feet above the high water line in Wenham Lake, and a 36-inch cast-iron pipe line conveys the water by gravity from this auxiliary collecting basin into Wenham Lake. After this is done, the total area draining into Wenham Lake was about 4,350 acres, of which about 305 acres was water surface. Some years thereafter there was a period of deficient rainfall, during which the water in Wenham Lake dropped to a dangerously low level, and the cities, therefore, made provision to pump water into Wenham Lake at time of heavy flow from a brook flowing from Norwood’s Pond, supplementing the supply by the partial flow from about 1.3 square miles. It is estimated that the yield in the average year is now about 6.5 million gallons, and in a dry year only about 4.7 million gallons a day. In the year 1914, the average daily draft from Wenham Lake was over 6,000,000 gallons. It can readily be seen, therefore, that the present situation is a menace to both cities. For some years past they have clearly foreseen the necssity of procuring an increased water supply, and the following steps were taken with this end in view: In 1910, a report on this subject was rendered to the cities of Salem and Beverly by Mr. William S. Johnson. In 1911. the State Board of Health was directed to investigate the matter of water supplies for these and other cities and towns, and a report was rendered in 1912. In the same year, other reports were made by Mr. Johnson and Mr. George A. Kimball. In the year of 1912, the prospect of a shortage of water had become so threatening that the appointment of a special commission was authorized by the legislature to consider the entire question in a comprehensive way, the purpose being apparently to fix a basis for the policy of the entire district in regard to water supply for the future. A report was rendered by this commission early in 1913, accompanied by reports from Allen Hazen, Consulting Engineer, of New York City, and Guy C. Emerson, Engineer to the Commission. The substance of their conclusions, so far as they relate to the cities of Salem and Beverly, was that those two cities could most wisely suppleme.-t their present supply by pumping at time of flood flow fromthe Ipswich River into Wenham Lake. Following the report, the legislature passed an act creating the Salem-Beverly Water Supply Board. Under this act the board has proceeded with the carrying out of the work to date. The general purpose of the act was to authorize the securing of an additional water supply for the cities of Salem and Beverly by taking water, under stated restrictions as to time, quantity and minimum flow in the river, from the Ipswich River at a specified point in the town of Topsfield to Wenham Lake; to authorize the purification of the entire supply of the two cities when required, and to authorize if and when required the construction of storage reservoirs in order to increase the quantity of water which might be taken from the river under the conditions stated in the act. The restrictions above mentioned are as follows: The total amount of water taken from the Ipswich River in any one year shall not exceed 2,500,000,000 gallons. Water may be taken only between December 1st and June 1st. Water may be taken only when the flow in the river is 20,000,000 gallons a day or greater. It was left entirely to the Board, subject to the approval of the State Board of Health, to determine the details of the project. The board retained the services of Hazen & Whipple to investigate the various phases of the problem, which included principally the questions of diversion, of storage, and of filtration. A comprehensive topographical survey was at once begun. The survey yielded information which enables us to set forth several different plans for storage in the river valley itself, and other prospective storage sites near at hand, and several different methods and routes for bringing water from the river to the lake, the best one of which resulted in a large reduction from the estimates that had been made for the probable cost of the additional supply. Preliminary plans and estimates were made and reports prepared upon this whole question. From all the conditions, however, it is obvious that the larger storage projects are for the rather distant future: and the smaller ones, while they may be needed before many years, are not imperative at once. Emphatic attention may also properly be called to the fact that, if some of the restrictive conditions in the act governing the taking of water could be modified, the addition of further storage to the system could be postponed for manv years. Efforts will undoubtedly be made in the future to secure a reasonable modification of some, if not all, of these restrictions, in order to take advantage of large flows that occur from time to time throughout the vear, but that will continue to run unnecessarily to waste so long as the act with its present wording remains in force. The act of 1913 specified the point of diversion from the river to be in the town of Topsfield. not more than 3,000 feet easterly of the New buryport turnpike bridge at Newburyport turnpike. It is supposed that it was fixed thus with the intention of placing the intake above the brook which runs down through the town of Topsfield. If this supposition is correct, some error was made, because the polluted brook just mentioned runs into the Ipswich River several hundred feet above the point of intake authorized in the act. Since the extension of the intake up the river was very expensive, and entirely unnecessary from the point of view of the hydraulics of the system, and since, moreover, there did not seem to be any practical advantage or any greater assurance of a satisfactory supply by carrying the intake above the outlet of Topsfield Brook, the exact point of diversion became a matter of prime importance. An appeal was, therefore, made to the legislature of 1914 for authority to divert the water at a point much further downstream than stated in the act of 1913, but although this measure was well supported by the representatives of the two cities, Salem and Beverly, before the Legislative Water Supply Committee, the act was not passed. Later on, in 1915, after the plans had already been prepared for carrying out the greater part of the project in accordance with the act of 1913, the legislature was again petitioned for authority to locate the intake some distance below the point specified in the act of 1913. This petition was successful, and a bill was passed amending that portion of the old act. The plans had been prepared with a view to anticipating this amendment, but could have been very easily modified to provide for carrying the intake upstream in case the amendment had not been secured. The principal condition specified in the amending act was that the Salem and Beverly Water Supply Board should assume all the expense of changes, or improvements, that might be deemed necessary within the watershed of the Topsfield Brook, in order to properly protect from pollution the supplementary supply thus drawn for those cities. In compliance with this provision, remedies are now being applied for a number of nuisances and points of pollution in this region. The plans for the works for the diversion of the water for increasing the water supplies of Salem and Beverly, were prepared by us in the fall of 1914. The problem of getting this auxiliary supply from the Ipswich River to Wenham Lake presented some interesting possibilities. The plans provide for taking the water from the Ipswich River just below, the bridge of the Newburyport branch of the Boston & Maine R. R., a short distance south of the village of Topsfield. From that point a canal extends in a southeasterly direction across the swamp a distance of about 10,000 feet. This canal is to have a bottom width of 20 feet at an elevation estimated at 4 feet below extreme low water in the river. The material through which the canal is dug is swamp, much underlaid by very fine sand. The material as removed from the canal is to be placed about equally on the two banks, leaving a berm of 10 feet. The banks are to be left approximately flat on top, in order that a road may be built later if desired, at a minimum of cost. The average depth of cut for this canal is about 9 feet and the maximum about 13. The specifications provide that the dredge used for this work is, at the completion of the work, to become the property of the Salem-Beverly Water Supply Board, which will thus enable them to maintain the canal in good condition from year to year. Much of the area was at first covered with trees and underbrush, which were largely cleared off along the line of the canal before dredging commenced. This work was done in the winter of 1914-15, while the surface of the swamp was frozen. The contract for the work was let in the early spring of 1915 to F. T. Ley & Company, of Springfield, Mass., and the work is now well advanced towards completion. At the southeast end of the canal lies the pumping station. The equipment at present is to consist of one centrifugal pump with a capacity of 25,000.000 gallons per day, to be driven by an electric motor. The floor of the suction well for this pump extends down slightly below the bottom level of the canal. The structure, which is of massive concrete reinforced with steel, is provided with suitable racks, screens and stop logs. It is designed for a capacity considerably greater than the pump now installed. Provision is also made in the pump-room for the installation of another pumping equipment of capacity at least equal to that now installed. The power for operating the pump is to be furnished under an agreement with the Beverly Gas & Electric Co. From the pump the water discharges through a 48-inch Venturi meter into a conduit leading to Wenham Lake. The length of this conduit is 2,866 feet. About 1,415 feet of this lies practically level on high ground, limiting the height to which water has to be pumped from the canal; 1,406 feet of the remainder lies on a slope falling rather sharply to the south from this high ground into Wenham Lake, and the carrying capacity required was, of course, obtainable on this steeper slope with a smaller size of pipe. This part of the conduit is, therefore, only 36-inch diameter. The 48-inch conduit and the greater part of the 36-inch is of concrete pipe, which was made on the ground by the Lock Joint Pipe Company. In the 36-inch line, a portion of the conduit crosses a swampy area and some 411 feet across this swamp was of cast-iron pipe laid on pile bents. At the point where the pipe discharges into Wenham Lake, the bank is to be protected to prevent washing. The lift at the pumping station is estimated to average about 20 feet for a flow of 25,000,000 gallons per day, and for the average stage of the river that is likely to obtain when pumping is permissible. The system is simple in design and should be quite economical of operation. The removal of some of the restrictions placed upon the diversion of water in the act of 1913 would enable the present works to serve without further additions for supply, and at very low cost of operation, for many years to come. The total cost of the works is now estimated to be about $100,000.
*Of Hazen, Whipple & Fuller, New York City. Abstract of paper read at New England Water Works Association Convention, New York, Sept. 7-9, 1915.
Photo courtesy “The Oregonian,” Portland, Ore.