Local Initiatives 



controls to mitigate stormwater runoff among the purposes of subdivision rules and 

 regulations. 



Several towns have used subdivision regulations to establish control 

 over drainage and stormwater runoff, to address both flooding and water 

 quality concerns. In Narragansett, for example, new regulations specifically require 

 that drainage plans be provided for all new subdivisions and commercial developments. 

 East Providence subdivision regulations provide the city engineer authority to require 

 installation of retention basins in flood hazard areas where runoff must be limited. 

 Charlestown, in an effort to address concerns regarding flood hazard as well as 

 contamination of salt ponds, requires that all subdivisions and both commercial and 

 industrial developments plan for stormwater runoff. Calculations must be based on the 2, 

 10, and 100 year frequency storm. 



Recommendations to Town Councils 



The Stormwater and Erosion Control Committee prepared a set of general 

 recommendations to towns, encouraging incorporation of stormwater 

 management objectives and appropriate site design into subdivision 

 regulations. In addition, the committee's technical recommendations on 

 stormwater management and erosion and sedimentation control should be 

 incorporated in detail into town ordinances to the maximum extent possible. 

 Provisions which nmy be incorporated into subdivision regulations, or adopted as planning 

 board standards include: 



1. Control stormwater on site to prevent degradation of siuface waters, depletion of 

 groundwaters, and exacerbation of flooding problems; 



2. Use detention basins to collect runoff from catch basins and drains; transpon piped 

 stormwater to detention basins rather than to surface waters; 



3. Use perforated pipes to recharge underlying aquifers. Use grassed swales and rip- 

 rapped channels as alternatives to subsurface stormwater drainage networks; 



4. Use dry wells or infiltration devices where appropriate to collect roof drainage; 



5. Collect parking lot runoff in catch basins (equipped with oil and grease traps) which 

 subsequentiy drain into detention basins. Schedule regular maintenance of traps 

 and detention areas; 



6. Place limitations on the impervious surface area of roads, driveways, and 

 sidewalks, consistent with minimum federal requirements to reduce surface area 

 contributing to runoff. Discourage use of curbs and berms except as specified in 

 the committee guideUnes. Encourage use of gravel driveways, road shoulders, and 

 walkways; 



7. Limit site impervious area to 10 percent Encourage use of gravel or porous 

 pavement to meet impervious area limit; 



8. Require that post-development peak runoff equal pre-development quantities; and 



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