Upper Merion supervisors approve several stormwater waivers and a fee-in-lieu, postpone decision on sinkhole-area dwelling

The Upper Merion Township Board of Supervisors on May 7 approved three sets of stormwater waivers for separate residential projects and a fee-in-lieu payment for a sinkhole-prone lot, and agreed to postpone action on a larger waiver package for a proposed house on S. Gulph Road.

In the most detailed review, Township Engineer Al Vennettilli explained that the property at 363 Radar Drive has no existing stormwater management and that proposed work to add an in-ground swimming pool would raise impervious area by about 852 square feet. He recommended waivers allowing a reduced basin berm top width (2 feet proposed instead of the 10-foot standard), a six-inch freeboard arrangement capped by an engineered spillway, and a perforated plastic outlet with a level spreader in lieu of a concrete outlet structure. Public commenter and property owner Fathima Afrah confirmed the engineer's site description. The board approved the three waivers in a unanimous 3-0 vote (moved by Supervisor Greg Philips; seconded by Supervisor Greg Waks).

Also approved were three waivers for 420 Alderbrook Drive, where a proposed pool and accompanying patio would add roughly 2,000 square feet of impervious surface and raise lot coverage from 13.7% to about 19.7% (the R-1 maximum is 30%). Vennettilli said the site is not in a known sinkhole area and can infiltrate runoff, and he supported owners' requests to use the Rational method for routing calculations rather than the SCS TR-55 method (the SCS approach is typically used for larger parcels), to allow a 2-foot berm top width, and to omit anti-seep collars at basin outlets for a shallow rain garden. The board unanimously approved those waivers (moved by Chairperson Tina Garzillo; seconded by Supervisor Greg Waks).

The board did not act on a six-waiver package for 444 S. Gulph Road, a vacant 20,750-square-foot parcel in a sinkhole-prone vicinity where a 4-bedroom single-family dwelling was proposed. Vennettilli described requested exceptions including use of the Rational method and PA DEP hydrographs in place of SCS TR-55, a reduced 3-foot berm top width (vs. 10 ft), a basin with 2.76 feet total depth and 1.75 feet of water storage elevation, smaller roof-collector pipe diameters than the 15-inch standard, and grading closer than 5 feet to an adjacent property line. Board members asked staff to obtain a tree-removal list from the contractor and to confirm replacement obligations under township ordinance; the item was postponed to the Business Meeting for further information.

Separately, the board approved a fee-in-lieu request for a new single-family residence at 507 Coates Lane. Vennettilli said the lot is very flat, located in a sinkhole-prone area and lacks nearby stormwater facilities, so an on-site basin would be infeasible; the applicant's fee estimate was $19,865.52, which the board approved by a 3-0 vote (moved by Supervisor Greg Waks; seconded by Supervisor Greg Philips).

Board members framed many of these approvals as accommodations for small residential lots, with the engineer noting that some modeling methods and design standards aimed at larger developments can be impractical on constrained parcels. When asked whether additional runoff would reach the Radar Drive basin area, Vennettilli replied that "not much at all," explaining the site's drainage pattern and proposed spillway arrangement.

The board directed staff to carry the Gulph Road follow-up items to the upcoming Business Meeting, where absent supervisors can participate and the board can review contractor-provided tree mitigation commitments.

Actions at a glance: three waiver packages approved (363 Radar Drive; 420 Alderbrook Drive) and one fee-in-lieu approved (507 Coates Lane); one waiver package (444 S. Gulph Road) postponed pending additional information.