Stormwater Mgt. – Wrentham


Regulations for Storm Water and Runoff Management

March 1991


These regulations for storm water management are intended to protect the public and environmental health by providing adequate protection against pollutants, flooding, siltation, and other drainage problems.


The storm water management design shall include a control strategy and plan for Source Control and Best management Practice (BMP) for any particular development or project and shall accomplish the following goals.


A. Reproduce, as nearly as possible, the hydrological conditions in the ground and surface waters prior to development.


B. Reduce storm water pollution to the “Maximum Extent Possible”

(MEP) using Best Management Practices (BMPs).


C. Have an acceptable future maintenance burden.


D. Have a neutral effect on the natural and human environment.


E. Be Appropriate for the site, given physical restraints.


F. Provide a sufficient level of health and environmental protection

during the construction phase.


An acceptable storm water management plan shall


1. Capture and treat the “FIRST FLUSH” of storm, usually the runoff from the first 2 inches of precipitation for a small land area or other value as may be designated by the Board of Health.


2. Not cause an increase or decrease in either the total volume of runoff discharged offsite, or total rate of runoff discharged offsite, as compared with the respective discharge offsite prior to the development. Such condition shall be required for storms of 1, 10, 50, and 100 year frequency events.


3. Include source controls and design of BMPs and Infiltration and Detention structures in accordance with procedures acceptable to the Board of Health such as are described in the following publications.


a. “Controlling Urban Runoff – A Practical Manual for Planning and

Designing urban BMP’s – Department of Environmental Programs –

Metropolitan Washington Council of Governments”


b. “Storm Water Detention for Drainage, Water Quality, and CSO

Management” – Peter Stahre and Ben Urbonas – Prentice Hall – 1990


C. ASCE Publications entitled “Design of Urban Runoff Quality

Controls”, 1988 and “Urban Runoff Quality – Impact and Quality

Enhancement Technology”, 1986


d. “Urban Surface Water Management’ – Stuart G. Walesh – John Wiley &

Sons Inc. – 1989


a. “Underground Disposal of Storm Water Runoff – Design Guidelines

Manual” February 1980 of the Federal Highway Administration –

Department of Transportation


f. “Erosion and Sediment Control in Site Development- Massachusetts

Conservation Guide – Volume 1”.


4. In cases where runoff infiltration cannot, in the opinion of the Board of Health, be appropriately implemented because of the possibility of contamination of water supply, or because of extremely poor infiltrative and permeability characteristics of the soil, the requirement as regards

volume may be waived by the Board of Health, provided the applicant provides such additional preventive measures to prevent any increase in elevation or duration of downstream flood elevations. Such additional measures may be, but are not restricted to, the construction of compensatory flood storage facilities and/or the creation of additional wetlands.


Poor infiltrative and permeability conditions are defined as a soil permeability of less than I X 10 -4 centimeters per second. Unless, in the opinion of the Board of Health, such testing is not applicable for a particular site, all permeability tests shall be in-situ field bore hole tests for permeabilities In the acceptable range as specified above. If permeability testing Is desired to be performed in soils of lesser permeability, laboratory tests for hydraulic conductivity shall be performed on undisturbed samples by the Falling Head Permeability Test using flexible membrane triaxial test cells with back pressure (Army Corps of Engineering Manual EM 1110-2-1906 Appendix VII).


5. If detention or retention ponds are utilized, slopes shall be no steeper than 4 horizontal to 1 vertical. Maximum design water depth shall not exceed three (3) feet except in permanent ponds. Minimum bottom slope for “dry” detention areas shall be two (2) percent. A safety bench, a minimum of 10 feat wide shall be provided. Detention or retention areas shall not be constructed within existing stream bed or wetland areas.


6. Not result In channelization of surface runoff offsite without the written consent of the owner of the land affected, In the form of a permanent grant of easement, recorded at the Registry of Deeds.


7. Include hydrologic and hydraulic calculations and data to support the proposed design for the runoff drainage system. Both volume and flow rate of runoff, before and after development, must be clearly stated and shall be in accordance with the specifications previously designated herein. Calculations shall be performed using the most recent procedures of the U.S.D.A. So-il Conservation Service such as are described in National Engineering handbook-Section 4-Hydrology (SCS 1985)., TR-20 “Computer Program for Project Formulation-Hydrology” (SCS 1983), and Technical Release No. 55 “Urban Hydrology for Small Watersheds” (SCS 1986). Structure design shall comply with the standards of USDA SCS Publication TR-60 for containments for detention and retention areas or other designated references. Additional design guidelines may be on file with the Board of Health.


The Wrentham Board of Health, Commonwealth of Massachusetts acting in accordance with Chapter 111, Section 31 of the Massachusetts General Laws and amendments and additions thereto, and by any other power thereto enabling, and acting thereunder have adopted STORMWATER AND RUNOFF MANAGEMENT REGULATIONS for the preservation of the public and the environmental health.


Voted on March 15,’1991, effective April 1, 1991


Wrentham Board of Health


Marion E. Caffei


L- t, Cler@


,t L. Peterson, Member