Stormwater Annual Inspection FAQ's

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Did you receive a Stormwater Annual Inspection Letter & Checklist from the Township? Here are some frequently asked questions to help you complete your inspection report.


1) Do I need to hire a professional engineer (P.E.) to do the inspection and report?

No – residents can complete the checklist and do a general, overall inspection of their systems and associated structures and report it back to the Township themselves.  Larger development projects, such as Land Development projects, will most likely need to hire P.E.’s to conduct and submit those inspection reports.
2) Can I submit the form electronically?

Yes – The Engineering Department would prefer that all Stormwater Annual Inspection Reports are submitted electronically.  E-mail your inspection report and/or any questions to

3) I've never received one of these notices/checklists before? Why am I receiving it now?

Since 2009, the Township has had in its Stormwater Ordinance requirements for permitted projects, one of which is that an annual report is to be submitted to the Township for any property that has obtained a stormwater and grading permit. The stormwater management system that is on your property was installed after 2009, so the installed stormwater system is required to be inspected and an annual report submitted to the Township each year to ensure the stormwater system is functioning adequately. The letter that was sent out to you was to inform and/or remind you of your operation and maintenance responsibilities. As a homeowner, you should be keeping detailed records of all of the maintenance and inspections that you are performing periodically throughout the year. Moving forward, the Township will be ensuring that all properties with stormwater systems are submitting their annual inspection reports on or before April 1st of every year.

4) I’m confused by the checklist, what elements do we need to inspect or review at our home?

The checklist is a general guide and doesn’t provide or ask all the questions.  Township residents can inspect and submit their Stormwater Annual Inspection Reports themselves, or they can hire a qualified professional engineer (with expertise in Stormwater Management) to do the inspection report.  The following is a listing of items that residents with individual on-lot stormwater systems, facilities and/or BMPs, should include in their inspections and reporting reports:  
Infiltration Beds (Underground):

Gutters – Are they free of debris?  Yes/No; If the answer is “no,” cleaning should be done by homeowner or contractor to remove debris, leaves, etc.

Downspout piping connections at corners of house at ground level: Are they intact, connected and not broken or cracked?  Yes/No; If the answer is “no,” they should be repaired or replaced to ensure water from the roof is traveling as designed into the system and to more importantly keep soil, mulch, leaves or debris from clogging the system or pipes.

Inlets – Yard Drains: Are the surface yard drains that collect surface water and convey it into the Underground Infiltration Beds clear of debris, intact and not broken or cracked, etc.? Yes/No; If the answer is “no,” they should be repaired or replaced and/or debris cleared.  In some location’s, debris may need to be routinely cleaned off the inlet tops or yard drains after each and every rainfall event, or at minimum, after all larger storms.

Inlets – Yard Drain Sumps: Inside of drains typically have a depressed area that is used to collect debris, such as water/leaves, mulch, rocks/soil, etc., that may enter the inlets or drains that feed into the beds.  Take cap off and look inside; if filled with water or debris, it can be cleaned with a typical shop vac or by small shovel or instrument, if necessary.  The importance here is to keep all fine debris, leaves, mulch, soil, and trash from clogging or destroying the functioning of these systems over time.

Observation/ Inspection Ports: Most of these underground infiltration beds are designed and constructed with a pipe coming out of the ground with a cap, which serves as an inspection port.  Take cap off and visually inspect to ensure that water drains completely within 72-hrs after a rainstorm.  Yes/No; If the answer is “no,” monitor to see if it remains full or overflows, which may necessitate further inspection by a professional.

Surface Areas Draining to your Underground Infiltration Bed: Is area draining to the bed clean, clear of any soil, mulch, etc. and is it fully stabilized?  Is the grass growth in good condition and uniform across the yard, etc? Yes/No; If the answer is “no,” then areas should be reseeded and stabilized with uniform coverage of grass, etc.  No soil, sand, or mulch, etc. should be piled up on top of inlets, yard drains, or within areas draining directly into your underground infiltration bed.

Overflow/Level Spreader: Is the outlet or level spreader working well and draining water during rainstorms? Yes/No; If the answer is “no,” any repairs, replacement needed should be scheduled or completed.  For example,  do you see any soil loss or erosion above the inlets, on slopes below the system in the yard or below the outlet or level spreader?  If yes, has maintenance been completed to repair or restore areas to approved plan condition?
Stormwater Basin (Aboveground):

Vegetation: Walking around the surface of the aboveground basin, outside of berm, inside of berm, basin bottom, and down-slope areas.  Is the vegetation in good condition, uniform grass growth and covering the entire ground surface?  In cases of a naturalized basin, is the basin bottom growing naturalized meadow mix or wetland vegetation per the approved plan?  Yes/No; If the answer is “no,” please reseed or address any areas devoid of uniform vegetation/grass coverage.

Inlet Structure: Typically, a concrete end wall and/or pipe discharge point where water enters the basin.  Is this structure in good condition, free of cracks and unimpeded to allow water flow into the stormwater basin?  Yes/No; If the answer is “no,” any necessary repairs should be made to ensure it remains in compliance with the approved stormwater permit plan.

Outlet Control Structure: Typically a concrete box or metal or plastic standpipe with small circular or rectangular orifice openings at various heights.  Is the structure free of leaves, soil/sediment build-up or sticks, trash or other debris, in accordance with approved plan?  Openings should be clear and open to allow water stored in basin during/after a rainstorm to slowly drain through the structure in a controlled manner and rate per the approved plan.  If debris is found, structure should be cleared and cleaned of all debris to ensure orifice openings functional, per plan.  If cracks or issues are noted, then repairs should be scheduled to ensure compliance with approved plan.

Pipes, Piping Drainage Networks: All basins typically have a network of piping which conveys water from specific yard drains/inlets above the basin, or directly from roof downspouts, and from the basin outlet control structure through the earthen berm to an outfall discharge location.  Pipe should be visually inspected to ensure it is intact and clear and clean of debris and devoid of any deterioration (seen in corrugated metal pipes [CMP]).  If necessary, repair or cleaning should be scheduled to clean or repair any items found from inspection.

Outfall: Basin Outlet Structures drain to a point and discharge at a concrete end wall structure, a single pipe, or a rock level spreader, etc.  Does the outfall appear in good working order with no signs of soil erosion at or downstream of the pipe or level spreader?  If not in good working order, these areas should be regraded, seeded and/or matted with erosion control blanketing to help seed grow below the discharge point.

Inlets/ Yard Drains: All Yard Drains and Inlets should be inspected to ensure they are clean and clear of debris on tops, and/or inside, and that they are intact and not cracked or broken.  Are all these drains/inlets in working order and free of any defects, or need of cleaning? Yes/No; If the answer is “no,” necessary repairs, replacement or cleaning should be scheduled and completed and described in your annual report.

Downspout piping connections at corners of house at ground level: Are they intact, connected and not broken or cracked?  Yes/No; If the answer is “no,” they should be repaired or replaced, to ensure water from roof is traveling as designed into the system, and to more importantly keep soil, mulch, leaves or debris from clogging the system or pipes.
Rain Garden (Aboveground/Belowground):

Rain Gardens: Typically are a combination of smaller surface basins with modified soils, some with underground infiltration beds and some without.  They generally contain a higher level of specialized plant material in the basin which is designed or intended to aid in water absorption and evapotranspiration (using and removing water from the system by use of the plants), in addition to the soils.

Items listed for both the Infiltration Basin (Underground) and Stormwater Basin (Aboveground) above would apply to inspection of these systems.
5) Do I need to provide anything else other than the inspection checklist with my Stormwater Annual Inspection Report?

Yes, please provide a brief explanation or narrative in your email or document describing your inspection and the general findings, repair or maintenance conducted during the calendar year.  Although the inspections reporting are to be submitted yearly, the Tredyffrin Township Stormwater Ordinance requires that property owners with these systems review and inspect their systems after storm events/rainfall to ensure they are functional and there are not visual issues or problems in the system or from the inlets/outfall where water enters/exists the system.  Providing a brief explanation of your inspection is useful to ensure that the system is inspected and condition is good, and systems are functional in accordance with the approved plans.  Photos are not required, but strongly suggested to keep with your records and to provide with your yearly inspection report.
6) Is there an approved Stormwater Permit or Plan for my property?

Yes, if you received notice, there is a prior approved stormwater permit and approved plan for your property.  If you do not have a copy of the permit/plan, you can contact the Township Engineering Department to obtain an electronic copy of the approved Stormwater Plan by emailing us at
7) Why do homeowners need to inspect these Stormwater systems, facilities or BMP’s?

The Tredyffrin Township Stormwater Management Ordinance requires that all applicable projects receiving stormwater permits from the Township provide for operation and maintenance of their permitted stormwater systems (Infiltration Beds, Basins, Rain Gardens, Green Roofs, etc.) on their respective properties.   Regular inspection, operation and maintenance of these stormwater systems ensures they continue to function as designed and that they remain in compliance with their permit.  Ultimately, inspections and maintenance helps property owners control their runoff and reduce downstream impacts to other Township residents and to our local streams, waterways, and infrastructure (roadways, bridges, culverts, buildings, etc.)