This action is brought by Kidde Manufacturing Company, Inc. against the Town of Bloomfield and the Borough of Glen Ridge, seeking damages for injury to its property caused by the negligence of the defendants in making improvements to a natural water course known as Toneys Brook. More specifically, it is charged that the improvements made by Glen Ridge upstream from the plaintiff's property increased the velocity of flow, eroded the stream bed and undermined the walls along the brook adjacent to the plaintiff's property and damaged a nearby building. The charge of negligence against Bloomfield is that its subsequent improvements downstream from the plaintiff's property further accelerated the flow and damaged plaintiff's property. Negligence is alleged in that each failed to take proper measures, in accordance with standard accepted engineering practice, to protect the plaintiff's property from the injurious consequences that would naturally follow from their respective improvements.
As to Glen Ridge, there is a further charge of negligence arising out of an alleged diversion of drainage from a 38-acre tract into Toneys Brook at a point upstream from plaintiff's property which further accelerated the velocity. There is no proof to support this allegation and it will not be discussed. [28 NJSuper Page 357] Toneys Brook rises in Montclair and flows in a general southerly direction through Glen Ridge and Bloomfield where it empties into Second River. The topography of the watershed of Toneys Brook is such that the brook has, for many years, been sensitive to flooding at times of heavy or sudden precipitation. This has been true since at least 1928 when there was litigation between Consolidated Safety Pin Company, a predecessor in title of plaintiff, and the Town of Montclair. See Consolidated Safety Pin Co. v. Montclair , 102 N.J. Eq. 128, affirmed O.B. 103 N.J. Eq. 378 (E. & A. 1928). The Consolidated Safety Pin Company property is the property now occupied by the plaintiff. The plaintiff's property lies on both sides of Toneys Brook with the main buildings on the east side, and on that side has a frontage along the brook of approximately 400 feet, the northerly or upstream end being approximately 135 feet downstream from the center line of Clark Street bridge. For years past the area near the Clark Street bridge in Glen Ridge was, from the point of view of floods, a critical area. To alleviate this condition the County of Essex, which maintains the Clark Street bridge across the brook, in 1922 raised the bridge about 13 inches, but this did not cure the situation. In consultation with the engineers of the State Water Policy Commission and of the County of Essex, a survey of the stream was made by the E.R.A. in 1934-5. Thereafter, Glen Ridge constructed 2,348 feet of rubble masonry walls and reconstructed 1,242 feet of rubble masonry walls on both sides of the brook, from the bridge to the Matchless Metal Polish Company plant some 440 feet upstream from the center line of Clark Street bridge. Subsequently it paved the stream bed from the Matchless Metal Polish Company bridge to a point 75 feet below the center line of the Clark Street bridge, a total in linear feet of 510. The paving operation required a lowering of the existing stream bed an average of about 18 inches and the laying of a six-inch smooth finish reinforced concrete flooring or bottom. The combined effect was to reduce the effective width to 20 feet, whereas the effective width had averaged more before the
work because of differences in width and because of some stretches of sloping banks which provided a wider channel in times of high water.
The purpose of walling and paving the stream was to expedite the flow past the Clark Street bridge sufficiently fast to avoid its backing up and overflowing the banks. The New Jersey State E.R.A. plan discloses that the proposed slope was to follow generally the slope of the stream at the time that the E.R.A. survey was made and it contemplated the lowering of the stream bed commencing at the Matchless Metal Polish bridge from as little as a foot and as much as two feet, and that the proposed slope was to be carried downstream some 600 or more feet to the point where the Delaware & Lackawanna Railroad trestle crosses Toneys Brook, and contemplated 50 linear feet of rip-rap immediately downstream from the Clark Street bridge. All engineers testified that the paving of the brook with a six-inch reinforced concrete flooring would reduce the friction and accelerate the flow. In 1937 the State Water Policy Commission advised Glen Ridge that "paving of the channel through Clark Street will undoubtedly transfer the trouble at Clark Street to the downstream end of the paving." The success or failure of the improvements in relieving floods seems to have been in a considerable degree dependent upon the point where a "hydraulic jump" was formed. A hydraulic jump is a place where the surface water is highest, i.e. , a point of greatest depth. One effect of a hydraulic jump is to lessen the velocity of flow and consequently the determination of its location was important. If too close to the Clark Street bridge, a control point or critical area, the jump would tend to slow the flow and create a backwater, and to the extent of the backwater nullify the accelerated run-off which the improvements sought. The State Water Policy Commission warned of this. It wrote:
"Because of the variable sections of channel below this point [Clark Street bridge], it is not practical to compute the location of this jump. We believe that if the paving is carried 100 feet below the outlet of Clark Street bridge, the jump will be formed
sufficiently below the bridge so as not to interfere with the low stage flow through this opening."
The Commission also warned that
"Paving of the Channel through Clark Street will undoubtedly transfer the trouble at Clark Street to the downstream end of the paving."
At about the same time Mr. Howard J. Finley, Engineer of Designs for Essex County, made a report with reference to the proposed schemes for alleviation of the critical condition at Clark Street, and noted that fieldstone paving, or rip-rap, was to extend 50 feet below Clark Street bridge. He also called attention to other matters as follows:
"For this plan the deepening will meet the present bed of stream 650 feet below the bridge. Walls for this distance ...