OVERHAUL AND SALVAGE… IN THEORY AND PRACTICE
Removing Water from Buildings— Dewatering Basements Presents Problems
THIS CHAPTER is a continuation of Part XI in which emphasis was placed on removing water from areas below the fire, but not from basement or cellar. In this article we discuss the problem of dewatering those belowground-level areas with some consideration also, of the part played by elevators and elevator shafts.
The reader is urged to bear in mind the general recommendations on removal of water from buildings contained in the preceding chapter, in his consideration of the following.
Actually, it does not matter how the water came to accumulate in the basement or sub-basement of a building, whether as a result of fire extinguishing operations carried on above ground level or in the sub-surface levels, or sprinkler failure. The main problem is one of dewatering the accumulated deposits.
True, where fire is fought above ground floor, some salvage operations of a flood-preventive nature can be carried out in the sub-surface areas where conditions make the maneuvers safe for the salvage personnel. Safety of life in any and all salvage operations comes ahead of saving of property. But in general, whenever any large scale fire extinguishing operations are undertaken, it is quite conceivable that water may accumulate in sub-surface areas faster than approved salvage dewatering operations can remove it, or prevent its entry into the areas.
Where personnel, because of hazardous conditions, are unable to operate in these areas, and open drains or otherwise prepare to forestall excess water accumulations, it is a foregone conclusion that water removal will be a major operation. This supports the contention advanced in the preceding chapter than under any and all conditions, dewatering operations should begin at the earliest possible moment, even if such operations are only of a preventive or precautionary nature, in anticipation of possible large scale water accumulation in these belowsurface levels. This presupposes, of course, that the fire is so located that salvagemen can enter the basement or cellar to (a) determine the equipment and/or stocks that may be damaged by water deposits; (b) shift or remove such of those stocks as may be possible; (c) prepare drains or other outlets to carry off the possible deposits.
Sub-surface fire salvage problems
Where the fire has originated in the basement or sub-basement areas, two salvage situations may arise. Either the fire has extended through-out the entire basement area or (2) the fire is confined to one portion of the basement.
When the fire has extended throughout the entire area, or the nature of the fire wherever it is makes the basement unsafe for operating personnel, salvage is generally confined to control of water that may be penetrating through walls into adjoining basement properties.
Control of such water may be possible by using stock covers as blocks and runways to confine and direct the water to available drains or other outlets. Either that, or pumping operations may be necessary if no drainage facilities are present.
Breaching basement walls may be called for
When conditions are favorable, it is sometimes advantageous to breach cellar walls at a point where the water can easily be directed to drains, or pumped out of the building. This method is particularly effective when the penetration of water through walls is taking place at a number of points.
Regardless of these measures, as soon as conditions permit, entry should be made into the fire building and the removal of water started immediately.
When fire is confined to one portion of the basement and conditions permit entry of personnel, the first action should be to hold the water to the smallest area possible by the use of covers as door blocks, and/or the flow of water should be directed to available drainage avenues, using covers as runways. Should the overall depth of water in an area call for it (and drainage facilities be inadequate for the task of dewatering), removal of water should be augmented by pumping.
A word or two about drainage. Few basements are without drains of some sort, either that, or they have the means for improvising drains, i.e., waste pipes, etc.
The breaking of waste pipes may be necessary, even though the basement is equipped with floor drains, and sump pumps are utilized at lowpoints.
Floor drains are often covered with stock, making them useless or the holes in the drain plates may be plugged with debris so as to render them insufficient to carry off the water rapidly enough.
Sump pumps are rarely of sufficient power and capacity to rid basements of heavy water accumulations fast enough and they eventually become inundated, or clogged with debris and thus become inoperative. Also, any power-operated sump pump or other type water mover may be deactivated by a power shutdown or failure.
It is general practice among insurance fire patrols when fire has reached serious proportions (usually indicated by multiple alarms), and the quantities of water that are, or will be, employed for the extinguishing process are beyond control, to attempt to locate and rupture if advisable, all waste pipe lines. When this is done, strainers should be inserted in openings to insure that debris will not clog lines.
Where conditions make it possible, and safe, efforts should be made to locate pits that are readily available for the insertion of suction lines at street level. Locating such deep points may be a tricky and dangerous business and considerable care should be exercised in such search. If building owners or occupants can be induced to indicate by placards or signs on nearby walls or posts where such pits and/or drains are located, it can be materially beneficial in helping locate them under water.
All water main supply lines, if possible, should be shut down to avoid any prolonged water discharge from broken or ruptured pipes. Also, electrical equipment in the areas, which might be damaged by water should be de-energized. Main switches, however, should not be pulled until and unless the fire forces operating above are notified.
Points for dewatering sub-surfaces
Briefly, here are the more important means of dewatering sub-surface areas such as basements and sub-basements (in addition to the use of exterior or above-ground pumps, eductors, etc.):
- Built in floor drains.
- Waste and soil pipes (connected with washstands, toilets, etc.)
- Connections or openings with adjoining properties (through which excess water may be drained or pumped and thence conveyed to safe points)
Special pump unit
The New York Fire Patrol has a special mobile unit which carries a variety of pumps capable of dewatering buildings, even under the most adverse conditions. Included are the following:
(At 6-foot lift) Two 120 gpm gas pumps
(At 12-foot lift) Two 60 gpm electrical driven submerged pumps
(At 6-foot lift) Four 20 gpm portable electrical driven pumps
(4 to 1, at 10
foot lift) Two eductors
(N. Y. Fire Department pumpers are employed to operate these devices) One 500 gpm pump, mounted on a trailer, which is used to supply eductors or for taking direct suction.
The Unit also carries gas-driven generator for supplying power to electrical driven pumps, and a variety of tools designed to assist in water removal.
Elevator shafts bane or blessing?
In the first part of this chapter we said that water finds its level. In so doing it takes the paths of least resistance. which are usually the vertical arteries, such as stairways and shaftways.
If these arteries or channels for the overflow can be dammed or otherwise blocked to detour the water away from, or out of these channels, and out of the building, or into areas where there is least possibility of water damage, this procedure is recommended. As was pointed out in the case of stairways, this method of shifting the channel by bagging or other means can often be done, but it is not so easy of accomplishment where the vertical artery is an elevator shaft. That is why it was recommended that where possible, waste water should be bagged or dammed on floors or diverted, and if necessary, chuted away from shafts.
At their best, elevator shafts are not the most desirable avenues for relieving floors of surplus water. Even though the most elaborate precautions are taken, and the elevators are rendered inoperable during operations, the possibility of water damage, through its finding its gravity level is always present. It appears to be the unanimous agreement among professional salvagemen that employment of elevator shafts to dewater upper floors of a structure should be done only where absolutely necessary. phase of salvage and should be given considerable thought. Basements are frequently the central location of the source of power need by occupants of a building in order to keep them in business.
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SALVAGE AND OVERHAUL —Continued from page 323
Nevertheless, it is agreed that every effort should be put forth to afford all possible protection to elevators. They are the first line of transportation at lofty fires and may be the means of saving fire fighters and salvagemen exhausting, back-breaking climbing up numerous flights of stairs and quite possibly rendering them incapable of performing any work upon arrival at the fire or water accumulation.
It may be considered a foregone conclusion that where basements exist and elevators serve below street levels, there are storages and/or machinery susceptible to water damage. The basement, therefore, is one of the first considerations to have the attention of the salvageman.
Value of pre-fire Inspections
Pre-fire inspection should acquaint the fire department, and it is to be hoped, the salvage corps, with the contents of basements; whether or not costly elevator or other machinery, heating and lighting equipment, as well as storages are located there. And at the same time, such advanced investigating should disclose the most available and advantageous means of removing accumulated basement water deposits. The more valuable and destructible the storages and other material located in below ground levels, the more important it is to chart beforehand the various outlets for dewatering and the methods that may have to be employed in the operation. And knowing the vertical arteries of all kinds is a requisite.
Dewatering operations for salvage purposes are not necessarily related to fire or its aftermath. Water damage, or threat of it, may arise from a sprinkler leak or breakdown, or from flood. For the most part, however, salvagemen are concerned with removal of surplus water resulting from fire extinguishment.
The source of the excess water to be removed, by one means or another, suggests to the experienced salvagemen the possible damage that it may do to stocks and building and also, the safest and best way to remove it.
Water that has drained through fire damaged materials carries with it debris of different kinds. This may be cinders and ash, damaged stock, even chemicals. In general, such accumulations result in “dirty,” if not dangerous water.
By contrast, water from a damaged or broken sprinkler system may be said to be “clean” water. Its foreign matter content will depend largely upon the kind of storage in the flooded area. Dewatering of this accumulation, therefore, is a cleaner, easier, safer job both for men and equipment, then ridding a fire building of its accumulated dirt and debris.
Water from nature’s floods is invariably foul and muddy and quite likely will contain grit, refuse and foreign matter mixed with the residue of the materials which it involves in basement or otherwise.
For the most part, dewatering operations involve removal of water, generally foul, from basements or subsurface area, and all possible precautions should be taken to see that the least possible damage is done to dewatering facilities.
Conclusions on basement dewatering
Removal of water from basements is a serious and possibly dangerous,
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Basements usually contain the main electrical power supply which, if interrupted, can causa complete shutdown of operation.
They are also the location of heating facilities which, if impaired, may have far-reaching effect on the ability of the concerns or residents occupying the structure to continue operations. Lack of heat makes the building unfit for human occupancy during the heating season. It permits freezing of water pipes, sprinkler systems and storage tanks. It has adverse effects on goods which cannot be subjected to low temperatures, but which are often stored in basements. And lack of heat to dry out a building usually results in excessive warping and possible formation of ice within the structure which later melts to cause unexpected and unnecessary damage.
Also subject to damage through basement flooding are refrigeration systems, particularly motors and compressors. Salvage operational reports indicate that interruption of refrigeration in certain occupancies has caused damage in excess of actual fire losses.
Mention has previously been made of elevator motors and equipment. The loss of transportation in a sizable building can not only seriously hamper fire fighters and salvagement but it can cause costly delays to the occupants.
Storage is indigenous with basements. Many below-surface areas in modern structures have large storage facilities, the contents of which would suffer extensive damage if water control in these sub surface areas was neglected.
A final detail is exposures. The fire forces may keep a fire from entering adjoining buildings above the street level, but if water is allowed to accumulate and reach excessive heights in basements, it will penetrate through walls and partitions quite possibly causing severe damage to the contents and facilities of adjoining occupancies.
The excellent diagrams used in this chapter are the work of Sgt. George Post, of the New York Fire Patrol.