Do I Need a Stormwater Plan?
How stormwater requirements work for additions, pools, patios, and other home projects in Pennsylvania.
Many Pennsylvania homeowners first hear about stormwater management when they apply for a building permit. A modest addition, pool, patio, or garage can trigger a municipal requirement for a stormwater plan, even on a property that has never had a drainage problem. Whether yours does depends on the project and on your municipality’s ordinance.
Why Municipalities Require It
Under Pennsylvania’s Stormwater Management Act, counties prepare stormwater management plans and municipalities adopt ordinances to carry them out. Each municipality sets its own thresholds and submission requirements, so a project that is exempt in one Township may need a plan in the next.
What Usually Triggers a Requirement
Most ordinances are based on new impervious area, meaning roofs, pavement, patios, pool decks, and other surfaces that do not absorb rainwater. Some also consider how much ground is disturbed. Common examples include additions, garages, pools and pool decks, patios and outdoor living areas, driveway expansions, and new homes.
Many ordinances count impervious area cumulatively, so earlier improvements on the property can affect whether a new project crosses the threshold.
Erosion and sediment control is required for any earth disturbance, even when a project is exempt from stormwater management.
How to Find Out
Start with your municipality’s stormwater ordinance, which is usually available on the municipal website or in its online code. The zoning or codes office can also tell you whether a submission is needed.
Elsa Associates can review the ordinance, account for existing and proposed impervious area, and tell you early whether a plan is required and what it will involve. When one is required, Elsa Associates designs a practical solution and prepares the documents for submission.
Municipal Guides
These guides summarize how stormwater requirements work in several municipalities Elsa Associates serves:
Derry Township (Hershey) stormwater requirements
Lower Paxton Township stormwater requirements
Manheim Township stormwater requirements
Learn More
For a broader overview, read our Stormwater Management Basics for Homeowners guide, or learn more about stormwater plans and reports.
Not Sure Whether Your Project Needs a Plan?
An early conversation can clarify what your municipality is likely to require before you finalize the design or apply for a permit.