7102 LOWER RIDGE RD 2018-07-25 - Laserfiche WebLink

t r BMP T5.13 "Post Construction Soil Quality and Depth" The top soils will be stockpile on-site and reused per "Implementation Options #3 per Volume V, Chapter 5, BMP T5.13 "Post Construction Soil Quality and Depth" which requires "Stockpile existing top soils during grading and replace it prior to planting... " In addition,the soils will be required to be tested for organic compliance. See the following requirements. BMP T5.13 Purpose and Definition Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions including: water infiltration;nutrient,sediment,and pollutant adsorption;sediment and pollutant biofiltration;water interflow storage and transmission; and pollutant decomposition. These functions are largely lost when development strips away native soil and vegetation and replaces it with minimal topsoil and sod. Not only are these important stormwater functions lost, but such landscapes themselves become pollution-generating pervious surfaces due to increased use of pesticides,fertilizers and other landscaping and household/industrial chemicals,the concentration of pet wastes,and pollutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the post development landscape,provides increased treatment of pollutants and sediments that result from development and habitation,and minimizes the need for some landscaping chemicals,thus reducing pollution through prevention. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of naturally occurring soil and vegetation. However,establishing a minimum soil quality and depth will provide improved on-site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost, composted woody material, biosolids,and forest product residuals. It is important that the materials used to meet the soil quality and depth BMP be appropriate and beneficial to the plant cover to be established. Likewise, it is important that imported topsoils improve soil conditions and do not have an excessive percent of clay fines. Design Guidelines • Soil retention. The duff layer and native topsoil should be retained in an undisturbed state to the maximum extent practicable. In any areas requiring grading remove and stockpile the duff layer and topsoil on site in a designated,controlled area,not adjacent to public resources and critical areas,to be reapplied to other portions of the site where feasible. • Soil quality. All areas subject to clearing and grading that have not been covered by impervious surface, incorporated into a drainage facility or engineered as structural fill or slope shall, at project completion, demonstrate the following: I. A topsoil layer with a minimum organic matter content often percent dry weight in planting beds,and 5%organic matter content(based on a loss-on-ignition test)in turf areas,and a pH from 6.0 to 8.0 or matching the pH of the original undisturbed soil. The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers,where feasible. 2. Planting beds must be mulched with 2 inches of organic material 3. Quality of compost and other materials used to meet the organic content requirements: 7102 Lower Ridge RD Full Drainage Report Revised:November 3,2017 Page 12