of Dam Safety
Low Level Outlet Policy
302 CMR 10.14 (7) requires a conduit to be provided to drain the impoundment.
This policy further clarifies 302 CMR 10.14 (7) (f) (5).
In the case when an alternative method(s) of drawdown is requested, the proponent shall submit reasons why a waiver should be granted (i.e.: contaminated sediment, funding issues, complexity of construction, etc). The request for waiver shall demonstrate that the water in storage can be moved out of the reservoir by mechanical means. The project design report shall include a detailed description of the pumps, siphons, etc. that would be necessary to remove the stored water in a reasonable period of time and maintain the reservoir in a dry state if necessary. A detailed drawdown plan, mustbe included in the design,that identifies the volume of water in storage, the rate of inflow under average inflow conditions, identification of pump equipment, or other means necessary to remove stored water and maintain a drawdown condition, time it will take to lower the water level, etc. The alternative drawdown plan shall be included in the required Operation and Maintenance Manual (O&MM) and in the Emergency Action Plan (EAP) if required.
In the case where an existing conduit is in poor condition (i.e. severely deteriorated, structurally compromised, leaky, etc) and the condition could compromise structural stability of the existing dam, the design report shall address the compromised conduit condition (relining, slip lining, grouting or other feasible means) and bring the existing conduit to safe and good condition.