Directly Resulted in The Loss of Thirty Lives

• Second deadliest natural disaster event to impact New Jersey in a century (See flooding safety tips)

Record Rainfalls

• Newark experienced an all-time record for highest one-hour rainfall total (3.65 inches)
• Documented 10+ inches of rainfall in parts of Hunterdon, Essex, Middlesex and Union Counties

Severe Flash Flooding Due to Intense Precipitation

• Storm sewers were overwhelmed
• Streams and rivers couldn’t convey so much water in such a short time
• More than 12 rivers exceeded their 100-year flood levels

Ida Compared with Existing Flood Hazard Rules

The current FHACA Rules set the design flood elevation (DFE) as the higher of:

• Flood elevation mapped by NJDEP
• FEMA 100-year elevation plus 1 ft

Ida case studies show average elevations of 3.1 feet above FEMA’s 100-year flood elevation

New Design Flood Elevation (DFE)

• To help protect communities from future flood damage, the DFE along streams and rivers will be raised by 2 ft above current standard.
• New DFE is the higher of:
  • Flood elevation mapped by NJDEP (where available) plus 2 ft
  • FEMA 100-year elevation plus 3 ft
• When calculating flow rates to determine DFE:
  • Compute flow rates based on future anticipated 100-year precipitation
  • Model design flood based on 125% of the computed flow rates

New Stormwater Management Standards

• Account for existing increased rainfall and prepare for likely further increases results in nominal additional effort or cost during development
• Achieve greater runoff and flood control with, for example, a 2% increase in the amount of property required for stormwater controls
• Deploy regulation consistent with Governor EO 100 approach of utilizing flexible standards commensurate with risk recognizing that no one-size fits all
• See potential increases in the size of stormwater BMPs to accommodate the adjusted rainfall amounts for a warehouse development in examples below