Post Construction Requirements

Basic Tier

New/Replaced impervious area < 2,500 sf

Tier 1

New/Replaced impervious area > 2,500 sf

New/Replaced impervious area > 2,500 sf

Tier 2

N/A

Net impervious area > 5,000 sf

Tier 3

Net impervious area > 15,000 sf

New/Replaced impervious area > 15,000 sf

Tier 4

New/Replaced impervious area > 22,500 sf

Type of Project

Performance Requirements

Exempt from PCRs

Runoff Reduction

·        Minimize runoff by redirecting downspouts to landscape

•     Utilize pervious paving material

·        Install a rain barrel

Tier 1

·        Projects, including single-family homes, that create or replace 2,500 sf or more of impervious area

Site Design and Runoff Reduction

·        Limit disturbance of natural drainage features.

·        Limit clearing, grading, and soil compaction.

·        Minimize impervious surfaces.

·        Minimize runoff by dispersing runoff to landscape or using permeable pavements

Tier 2

·        Detached single-family homes that create or replace 15,000 sf or more of net impervious surface.

·        All other projects that create or replace 5,000 sf or more of net impervious surface.

Water Quality Treatment

·        Meet all Tier 1 requirements

·        Treat runoff with an approved and appropriately sized LID treatment system prior to discharge from the site.

Tier 3

·        Projects including single-family homes that create or replace 15,000 sf or more of impervious surface.

Runoff Retention

·        Meet all Tier 1 and Tier 2 requirements

·        Prevent offsite discharge from events up to the 95th percentile rainfall event using Stormwater Control Measures.

Tier 4

·        Projects that create or replace 22,500 sf or more of impervious surface.

Control Peak Flows

·        Meet all Tier 3 requirements

·        Control peak flows to not exceed pre-project flows for the 2-year through 10-year events.