Retrofit catch basin for use in storm water management practice

A stormwater diversion and overflow device, the device comprising:

• a grate assembly,
• the grate assembly comprising a grate, a cover, and a structural frame,
• the grate defining a first side, a second side opposing the first side, and a volume between the first side and the second side,
• the grate comprising an outer wall connecting the first side to the second side and extending at least part way around the volume, the outer wall defining a third side, a fourth side, and a fifth side of the grate,
• the grate comprising at least a first opening extending through the grate from the first side to the second side, at least one of the at least a first opening extending through a sixth side of the grate,
• the cover comprising a plate, being directly on the first side of he grate, and bounding each at least a first opening on the first side of the grate,
• the cover configured to cover an existing street-side catch basin,
• the cover configured to divert stormwater runoff off a street through a curb inlet structure shared with the existing street-side catch basin to an alternative stormwater management practice system before the stormwater runoff enters the existing street-side catch basin,
• the cover bounding at least a portion of each at least a first opening where each at least a first opening extends through the sixth side of the grate, the cover configured to pass stormwater runoff from the alternative stormwater management practice system to the existing street-side catch basin,
• the grate set in the structural frame,
• the plate extending beyond the grate and the structural frame by an amount sufficient to carry the stormwater runoff to the alternative stormwater management practice system.