The Tarheel Pipeline, Fall 2015

evere weather can be devastating, and according to numerous weather

sources is occurring more frequently and widespread. Tornadoes are

now occurring anywhere from the Rockies to the east coast. Currently,

the southern pacific coast is experiencing a severe drought, many

areas in the east coast are flooded, and thousands of people were killed

in the Nepal earthquake.

Severe weather does not discriminate, and it can damage or destroy

everything in its path including water tanks. Necessary water supply

for consumption, fire protection, and emergency needs is crucial to

everyday well-being, and even more when a severe weather event

occurs. Therefore, water tanks should be designed, constructed,

maintained, and inspected to withstand severe weather.

Tanks that have experienced winter storms and freezing should

obviously be inspected for damage, but seismic activity, high winds,

lightning, droughts, and flooding also occur in the summer months

and tanks are susceptible to damage from them as well.

HIGH WINDS/LIGHTNING STRIKES

National Fire Protection Association (NFPA) states, “Anchor bolts

shall be arranged to securely engage a weight at least equal to the

net uplift when the tank is empty and the wind is blowing from any

direction

.” Lightweight tanks definitely need to be anchored against

high winds in areas that experience them, and elevated water tanks

should have their windage rods inspected and tightened regularly to

maintain winds of 150 mph, blowing from any direction.

Tanks not grounded are subject to lightning damage. Lightning strikes

could cause power outages that could affect the ability to receive water.

Water pumps and alarms could malfunction, or a complete tank failure

could occur. NFPA 780 states, “Tanks shall be grounded to conduct

away the current of direct strokes and the buildup and potential that

cause sparks to ground

.”

DROUGHT/FLOODING

When a drought occurs, aggressive

water conservation measures are

often taken; but tanks still need to be

inspected and cleaned. To conserve

precious water, Robotic Operated

Vehicles (ROVs) can be used to

inspect and clean tanks without

draining them, thus saving the water.

Foundation damage can easily occur if tanks are subjected to flooding

for prolonged periods. Tank sites should have good drainage to

minimize or prevent possible foundation damage from flooding. The

site design should also include provisions for draining the tank and

the discharge from the tank overflow without damaging the tank site

or neighboring properties.

SEISMIC ACTIVITY

Tanks are designed and constructed for resisting earthquake damage

by complying with the earthquake design load provisions of American

WATER TANKS & SEVERE WEATHER

Fall 2015

NCRWA.COM

feature

By Erika Henderson, Pittsburg Tank & Tower Group