The optimal depth in a birdbath is two and a half inches.
The Boston Redevelopment Authority (BRA) oversees proposed projects within the Groundwater Conservation Overlay District under Article 32. To review this document, visit the BRA's webstite. Article 32 prevents the deterioration and, where necessary, the restoration of groundwater. Any Applicant seeking a building permit for a proposed project within a Groundwater Conservation Overlay District shall be subject to the requirements of Article 32 where such Applicant seeks:
The results will tell you if the property is in the Ground Water Conservation Overlay District or not.
In addition to complying with the BRA’s Article 32, Boston Water and Sewer Commission (BWSC) will review plans verifying that a suitably designed infiltration system equivalent to no less than 1.0 inches across the portion of the surface area of the lot occupied by the proposed project; and for substantial rehabilitation projects, it will be for lot areas occupied by the structure. This system shall be designed so that no negative impact occurs on neighboring sites.
The developer shall provide plans and calculations for the proposed infiltration system. The calculations shall demonstrate that the internal capacity of the infiltration structure and surrounding stone void space (maximum 30%) is greater than 1 inch of rainfall across the impervious area. The calculations and infiltration system must be stamped by a Professional Engineer registered in Massachusetts.
The developer must obtain a license from the Public Improvement Commission if the infiltration system proposed is located under the public way (sidewalk or roadway). For more information, please visit the Public Improvement Commission's website..