Woburn conservation commission hears informal request to keep crushed blast rock on steep Delaney slope

George Ryan, a civil engineer with Stantec, told the Woburn Conservation Commission on June 13 that the applicant requested a minor modification to change the cover material on a steep north slope at the Delaney at the Vail senior housing site (ED 348‑826) from a 6‑inch loam and seed meadow to open‑graded crushed rock and riprap.

Commission member Janet said the site’s subsurface detention system manages Delaney’s runoff and that the slope as built allows water to percolate through the crushed rock; she said the change is unlikely to produce a significant stormwater management difference but will reduce meadow vegetation and the habitat that would attract pollinators and ground‑nesting birds. "It wasn't being managed any other way but what hit it," Janet said when describing how the original meadow would have functioned.

The commission’s chair and other members pressed the applicant to document the hydrologic differences between the as‑designed meadow and the as‑built rock cover. Commissioner DeJos and others asked for simple comparative calculations showing flow rates and velocities from the as‑designed to the as‑built condition; George Ryan said no formal recalculation had been prepared but that underground stormwater utilities were submitted and approved and that, in his professional judgment, the material change made a nominal difference for the system's peak rates. "From our work and in my professional judgment, the change in material...is nominal," Ryan said.

Members also raised non‑hydrologic concerns: commissioners called the riprap appearance "industrial" compared with the planned meadow and noted loss of habitat for birds and pollinators. Multiple commissioners suggested seeking a middle ground—screening, targeted planting between rock voids, or a compromise cover—rather than removing the rock or forcing full restoration if that would worsen erosion.

The applicant said the rock resulted from earlier site earthwork and blasting and argued placing topsoil and seed on the steep, blasted slope risked erosion and topsoil loss before vegetation could establish. The commission characterized the matter as an informal discussion and instructed the applicant to consider the comments and, if they return with a formal modification request, to provide the requested runoff comparisons and any proposed compromise designs. No formal vote was taken at the June 13 meeting.

Next steps: the commission asked the applicant to prepare comparative runoff calculations and consider design compromises addressing screening, habitat, and aesthetics before returning with a formal filing.