Patent attributes
A watertight manhole insert and tether locking apparatus and method of use designed to prevent unauthorized entry into a sanitary sewer or other closed drainage system through a manhole closed by a manhole cover. The manhole insert is located beneath the manhole cover and is connected to the manhole by a tether apparatus in the manhole to prevent water entry into the manhole, theft of the manhole insert and to deny access to the manhole. The manhole insert includes a pan-shaped insert body having pressure-relief valve and a lift strap and a side wall fitted with a top rim for engaging a shoulder shaped in the manhole, to support the manhole insert in the manhole. In a preferred embodiment one end of a flexible stainless steel tether is connected to the bottom side of the manhole insert and the opposite end extends through a pair of oppositely-disposed anchor rings fixed to the manhole wall beneath the manhole insert and then through an opening in the manhole insert and a locking device on the top of the manhole insert. When the manhole insert is placed in the manhole, the tether is tightened in the anchor rings as it is pulled upwardly through the locking device and is locked at the locking device.
