Flood risk control
Flood Risk Management for Preventing Property Losses
Flood loss scenario the world over as well as in India seems to be spiralling upward at an increasing rate than in the past. Besides climate change the other factors that have contributed to this increasing trend are: human modification of the landscape, changes in discharge path of drainages, settlement in areas near to water bodies, high value accumulation, higher vulnerability and lack of risk awareness amongst property owners. This increasing trend in flood losses is a cause of major concern both to the property owners and as well as to the insurers. This article gives a thumbnail sketch of the various loss prevention measures that can be taken to mitigate flood loss.
Flooding can be caused by bodies of water (rivers, streams, oceans, bays, lakes, canals, etc.) overflowing their normal boundaries, or as the result of storm water runoff accumulating in normally dry areas. Protecting a facility from the negative effects of flooding, however, is not as simple as merely locating it outside known flood zones; inappropriate site layout and building design can create a storm water runoff flood exposure anywhere. In addition, off-site flooding can block access routes to and from the site, as well as interrupt vital utilities. Risk control measures that need to be in place to mitigate flood hazard during the entire event stages namely: pre-event, event and post event periods are listed below.
Ten point property protection checklist for flood risk
Proper site selection is the best mitigation measure against flood damage. Better site selecting is far easier to implement than designing a facility located in a flood prone area from getting flooded. Besides the location all access routes (highway, railroad, etc.) should also be located outside flood zones to permit access during flooding incidents that may take place in a city.
When facilities are located inside flood prone areas the risk of flooding is greatly reduced by elevating the entire site level such that this is higher than the highest predicted flood level for a 250 year return period for flood. Where elevating the entire site is not possible, it then becomes necessary to determine which buildings and areas of the facility are more likely to be flooded and focus on minimizing the impact of flooding in these areas through building design and by providing higher plinth heights.
Ensure water runoff originating from off-site areas is included in the facility’s site water management plan. During unusually heavy rainfall, the lack of drainage capability may cause water to enter premises and buildings which may not have been generally considered during initial design. Also use grates, trash racks, curbs, etc. to protect the inlet to all drains and storm-water drainage systems against debris blockage. Do not use landscaping materials, such as wood chips, pine needles, etc, as these are easily displaced by rain water. They may obstruct or clog drainage systems, catch basins, culverts, or overland flow patterns.
Install backflow preventers equipped with manual shut-off valves on effluent-discharge lines that are connected to combined sewer systems (wastewater and storm-water runoff) to avoid back flow.
5.Inspection and Maintenance
Check and maintain roof anchors to help prevent collapse or “blow off” of roof due to strong winds as this can cause subsequent water damage. Have in place a program to check and clean all roof drains, internal drainages and external drains around factory premises periodically especially before and during the monsoon season. Also inspect and check roofs for uncovered roof openings and windows for proper closing and broken glass panes to prevent possible water entry through such openings. Check and maintain all de-watering pumps to ensure that they are fit for operation during an emergency. Diesel driven de-watering pumps (Main or stand-by) would become handy in case of a power failure.
Flood gates, stop logs, water barrier tubes, etc. are engineering measures that help prevent water entry. Protecting door openings of flood prone areas with raised sills is another feature that helps control flooding. An alternative but less reliable immediate solution is to use sandbags as an emergency stop gap measure.
In the event of imminent flooding shift all valuable stock and property to higher floors, elevated locations, or safer places. Also switch off/ disconnect power supply by switching of mains as this can help prevent possible short circuits. Motors of pumps and machineries such as lathes which have motors at floor level could be disconnected and removed to safer locations. Provision of skids under all floor-stored stock including sheet and coiled metal helps prevent damage from any water accumulating on the floor. Quenching oil in open pits should be emptied and stored in drums as water entry into pits could result in a property loss. Also identify hazardous materials or other stored chemicals that could be flooded and relocate these or move them to higher locations.
For minimizing the extent of damages after a flood event inspect and clean the flood ravaged area as quickly as possible. To accomplish a fast cleanup, power and HVAC systems have to be restored on priority. Heating of motors checking their insulation resistance values before taking them into service, drying of electronic equipment etc. are other measures that need to be initiated. Prioritize activities regarding repair/ replacement of equipment giving priority to equipment that are most critical for resumption of operations. Regarding buildings check for structural damage. Also check the ceiling for signs of sagging. Make a hole at the edge of the sag to drain accumulated water. Patch holes in the roof, walls or windows with boards, tarps or plastic sheeting. Make arrangements with contractors who can help clean up and assist in post-flood repairs. Check all flammable liquid storage and flammable gas piping systems for leaks before commencement of operations. Also all combustible debris that accumulates should be removed.
9.Flood Emergency Response Plan
For locations prone to flooding establish a formal written flood emergency response plan (FERP). A designated individual who has authority to activate the plan, including halting business activities as necessary, with alternates to cover all working periods should be in charge. In addition, identify specific tasks that will be assigned to available personnel. For each structure, identify areas and floors that are likely to be flooded, and ensure that they are used solely for non-essential operations. A procedure that describes the steps to shut down/de-energize utilities in an orderly manner to reduce ignition sources and the amount of damage should also be documented.
A plan to put fire protection systems into service promptly after the incident should be in place and should be implemented immediately after the incident. Also examine the fire pump water source (particularly for open bodies of water) to ensure debris are not clogging the pump suction lines of the fire protection system.