Journal of The New England Water Works Association - June 2015 - (Page 99)

Salem's Folly Hill Reservoir: Inspecting and Rehabilitating a Century-Old Concrete Tank By Jeffrey E. Diercks, P.E.,* David H. Knowlton, P.E.,** Lisa H. Gove, P.E.,*** and Kevin D. Gallerie, P.E.**** Presented September 23, 2014 ABSTRACT 2014 marked the Centennial of Salem's Great Fire of 1914, when lack of water pressure for firefighting contributed to the destruction of 251 acres of the City's heart. The fire led to the 1915-16 construction of the 10.5-MG Folly Hill Reservoir, now one of the oldest concrete reservoirs in the state. In 2011-12, this football-field sized tank was drained and chemically cleaned to perform structural inspections and concurrent mixing system installation. A major rehabilitation program is scheduled for 2015 completion, including structural repairs and a roof liner. Figure 1 - The Devastation of the Great Fire Photograph courtesy of the Phillips Library, Peabody Essex Museum, Salem, Mass, taken the day after the fire (Kampas, 2008) History of the Reservoir Water system pressure issues were the major contributing factor to the devastation of the Great Fire of 1914 (see Figure 1). Many of the buildings in the path of the fire were of threestory or greater construction, but at times the hose streams could not reach above the second floor. In the aftermath of the fire, the City instituted sweeping changes in building codes and major initiatives in water system improvements. At the time of the fire, the Salem distribution storage reservoir had an overflow elevation of only 145 feet. The City received legislative approval to purchase land for a new reservoir atop Folly Hill in Danvers. With a summit elevation of over 200 feet, Folly Hill offered the ability to significantly improve water pressures in downtown Salem. Design of the new reservoir was completed in 1915. The reservoir was constructed in 1915-16 (see Figure 2). When the new transmission main connecting the supply source (Wenham Lake), *Associate, CDM Smith, 670 North Commercial Street, Manchester, NH 03101, (603) 222-8335, diercksje@cdmsmith.com **City Engineer, City of Salem, Salem, MA ***Associate, CDM Smith, Boston, MA ****Structural Engineer, CDM Smith, Boston, MA Figure 2 - Reservoir Wall Construction Pouring concrete for the reservoir wall. Note the trestle at right, for delivering materials. (Conant, 1916) Folly Hill, and downtown Salem was completed in 1917, the reservoir was placed into service. In 2001, a robotic vacuum cleaning procedure removed sediment from the reservoir for the first time. Diver inspections in subsequent years indicated the presence of root intrusion through the roof and limited areas of minor spalling. In view of the age and uncertain condition of the reservoir, its criticality to the Salem drinking water system, and per recommendations from CDM Smith, the City ordered a thorough cleaning and structural inspection to take place in 2011-12. This is believed to be the first in-the-dry entry to the reservoir since some 1927 repairs, 84 years earlier. The results of the inspection led to the design of the 2014-2015 rehabilitation program. Journal NEWWA June 2015 99

Table of Contents for the Digital Edition of Journal of The New England Water Works Association - June 2015

Officers of the New England Water Works Association
NEWWA 2015-2017 Meeting & Event Schedule
On The Cover
Cyanobacteria in Reservoirs: Causes, Consequences, Controls
With a Little Help from our Friends: Collaborating to Protect a Water Supply
Salem's Folly Hill Reservoir: Inspecting and Rehabilitating a Century-Old Concrete Tank
Restrained Joint Ductile Iron Pipe Proven Reliable for Stressful Utility Installations
Water System Profile: Southington, Connecticut Water System
Proceedings
Urgent Need for Papers!!
Obituaries
Guidelines for the Preparation of Papers for Publication in the Journal of the New England Water Works Association
Guidelines for the Peer Review Option of the Papers Appearing in the Journal of the New England Water Works Association
Index to Advertisers

Journal of The New England Water Works Association - June 2015