New Orleans Stormwater Regulations and Green Infrastructure Toolkit

Transcription

1 New Orleans Stormwater Regulations and Green Infrastructure Toolkit City of New Orleans Tulane Engineering Forum Urban Green Infrastructure April 20, 2018

2 Drivers Planning Modify zoning and subdivision regulations to encourage on-site storage and filtration of stormwater. City of New Orleans 1

3 Drivers Clean Water Act You must: continue to implement and enforce a program to address stormwater runoff from new development and redevelopment projects that disturb greater than or equal to one acre Your program must ensure that controls are in place that would prevent or minimize water quality impacts. City of New Orleans 2

4 Stormwater Code Components Construction Requirements Post-Construction Requirements Simplified Procedure Fee-in Lieu Annual Certification City of New Orleans 3

5 Stormwater Code Construction Requirements Enhanced erosion and sediment control requirements for all construction sites Silt fencing and catch basin protection Concrete waste management Concrete washout facilities City of New Orleans 4

6 Stormwater Code Post-Construction Requirements Thresholds New Construction of 5,000 or more SF of impervious surface Substantial improvement of a site with 5,000 or more SF of impervious surface Any site over an acre Any site where principal use is stormwater management Any addition or replacement of impervious surface which results in 5,000 or more SF of impervious surface Exemptions for single and two family and residential dwellings under 6 units Additional exemptions for pavement maintenance and tenant build-out projects City of New Orleans 5

7 Stormwater Code Post-Construction Requirements Compliance Standards Detain or retain and filter 1.25 inches of stormwater Entitled to a 10% bypass No increase in runoff rate for a 10 year, 24 hour storm Reduction in Total Suspended Solids of 60% for new developments and 40% for substantial improvements City of New Orleans 6

8 Stormwater Code Fee-in Lieu Intended to apply to sites where compliance is impractical Must provide documentation of attempts to design a compliant plan, calculations, and cost estimates of possible solutions Rate is $44 per cubic foot of required storage Based on cost data collected from the past 2 years, Raftelis analysis At this rate, approximately 20% of projects would likely pay the fee City of New Orleans 7

9 GI Toolkit Overview Product that helps both public and private entities through the design process of Green Infrastructure Projects Improve the success rate of Green Infrastructure in New Orleans Allow the City to collect data on the aggregated benefit of Green Infrastructure in the Parish City of New Orleans 8

10 GI Toolkit Components Stormwater Calculator Standard Details covering 8 GI Types Supplemental Specifications Guidance Document including expected maintenance and lifecycle costs Plant List City of New Orleans 9

11 GI Toolkit Calculator Utilized to: Determine compliance with the storage requirement to detain the first 1.25 of rainfall from a site. Compare Pre- and Post-development peak runoff rates Compare Pre- and Post-development pollutant loads Excel based spreadsheet with five main tabs Instructions Summary Pre-Development Post-Development Water Quality 4 drainage areas included Not intended to replace hydraulic modeling when required City of New Orleans 10

12 GI Toolkit Details Bioretention Cell Bioswale Stormwater Planter Infiltration Trench Pervious Pavement Tree Cells Retention/Detention Basin Typical Details City of New Orleans 11

13 GI Toolkit Typical Details City of New Orleans 12

14 GI Toolkit Typical Details City of New Orleans 13

15 Article 23 Successes Over 120 projects approved by CPC since adoption Over 17,600,000 gallons of stormwater approved for detention City of New Orleans 14

16 Article 23 Successes City of New Orleans 15