Theft of municipal manhole covers is not only costly for the city involved, but can be very dangerous to the people that drive over the open hole. These old, 90-pound covers are sold by thieves as scrap metal. Some municipalities have switched to a bolt-down manhole cover that makes it much harder for a thief to steal, saving money and ensuring the safety of the public. You can install retrofitted bolt-down manhole covers using specially-designed replacement parts.
Determine the diameter of the manhole cover that needs to be replaced. Standard manhole sizes range from 22 to 48 inches in diameter. Make sure you have the correct size by measuring the inner diameter of your manhole using a tape measure.
Install the galvanised manhole skirt into the existing manhole. The skirt is a metal ring cemented into the inside of the top of the manhole, acting as a sleeve to which the new cover can be bolted. Mix the cement according to the manufacturer's instructions and apply a layer of cement to the outside edge of the sleeve. Slide the sleeve into the manhole and allow it to dry overnight.
Install the metal bolt-down ring on the top of the manhole skirt. The ring will be used to attach the cover to the skirt. Using an adjustable wrench, tighten the bolts on the ring to the top of the manhole skirt.
Bolt the manhole cover to the top of the manhole. Lay the weatherproof cover over the manhole and line up the bolt holes. Using an adjustable wrench, tighten the cover down completely, sealing the manhole from the weather. Insert the included plastic covers over the bolts to keep the bolts from being damaged by traffic and weather.