Common use of Design Process Clause in Contracts

Design Process. The first step in applying natural hydrology site design is to identify, delineate and assess the functions of all existing natural resources and natural and man-made hydrologic features that: are located within the project site; will receive discharge from the project site; or, may be impacted by runoff or disturbance from the proposed land development project. This includes: • Streams, waterways, springs, wetlands, vernal pools, and water bodies; • Drainage patterns, conveyances and discharge points; • Natural infiltration areas and patterns; • Areas of natural vegetation that provide significant evapotranspiration, pollutant removal, bank stabilization, flow attenuation, or riparian buffer functions; • Floodplains; and • Other features that contribute to the overall hydrologic function and value of the site and its receiving streams. Once this inventory and assessment are completed, these identified resources and features are then prioritized for their ability to provide hydrologic function and performance for managing runoff from the proposed site improvements. Specifically, they should be prioritized as follows: • Those to be incorporated into the site design in a manner that provides for their protection from any disturbance or impact from the proposed land development; • Those to be protected from further disturbance or impact and for which the proposed land development will provide improvement to existing conditions; • Those that can be incorporated into and utilized as components of the overall site design in a manner that protects or improves their existing conditions while utilizing their hydrologic function (e.g., for infiltration, evapotranspiration, or reducing pollutant loads, runoff volume or peak discharge rates, etc.) to reduce the need for or size of constructed BMPs; and • Those that may be considered for alteration, disturbance or removal. These prioritizations are then applied as the basis on which to begin the site design lay-out, grading, construction, and permanent ground cover designs to achieve the five (5) Design Principles outlined above. The following section describes just a few of the many design practices, methods and techniques that are available to achieve the landowner’s desired land development goals and the desired environmental efficiencies intended by natural hydrology site design. Table B.1 – Site Design Process Principles and Techniques Design Principles Design Techniques Minimize land disturbance – both surface and subsurface. • Maintain the natural soil structure and vegetative cover that are often critical components of maintaining the hydrologic functions of natural infiltration, bioretention, flow attenuation, evapotranspiration, and pollutant removal. • Protect, or improve, natural resources to reduce the needs for environmental mitigation, future environmental restoration, and cumulative flow and water quality impacts of unnecessary disturbances within the watershed system. • Minimize the disturbance of natural surface and groundwater drainage features and patterns, discharge points and flow characteristics, natural infiltration and evapotranspiration patterns and characteristics, natural stream channel stability, and floodplain conveyance, etc. Minimize the cumulative area to be covered by impervious and compacted surfaces. • Minimize the size of individual impervious surfaces. • Separate large impervious surfaces into smaller components. • Disconnect runoff from one impervious surface to another. • Avoid unnecessary impervious surfaces. • Utilize porous materials where suited in lieu of impervious materials. Designing to the land, so that the layout of constructed and landscape features utilizes the natural topography and minimizes grading. • Prioritize on-site hydrologic features (i.e., for protection, improvement, utilization, or alteration) and natural site drainage patterns and infiltration characteristics and consider them for the cornerstones of the conceptual site design. • Reduce grading and compaction by applying selective grading design methods to provide final grading patterns tthat preserve existing topography where it most benefits natural hydrologic functions and where needed; this results in graded areas that evenly distribute runoff and minimize concentrated runoff flows. • Consider the scale and placement of buildings and other infrastructure to minimize impact to natural hydrologic features. • Incorporate unique natural, scenic, and historic site features into the configuration of the development, and ensure flexibility in development design to meet community needs for complimentary and aesthetically pleasing development, such as can be achieved through Conservation Design and Sustainable Design approaches. Design Principles Design Techniques Design the constructed stormwater management system to take advantage of the natural hydrologic landscape to achieve the required stormwater runoff control standards. • Incorporate natural hydrologic features that have been selected for their available capacity and function into the overall system of site runoff controls. • Incorporate Low Impact Development (or similar) BMPs and distribute storm flows to: o Reduce runoff; o Manage stormwater at or as close to the point of generation as possible; o Disconnect discharges from streets and municipal storm sewer systems; and o Select and design BMPs to give first priority to nonstructural and vegetation (landscape-based) BMPs, second priority to surface structural BMPs, third priority to subsurface structural BMPs, and design subsurface BMPs as shallow as possible. • Provide open channel conveyance, as needed, to: o Treat water quality; o Reduce runoff velocity; and o Promote infiltratation and evapotranspiration of runoff. • Manage remaining conveyed stormwater from small storms in common open space areas to achieve multiple objectives: o Disperse storm flows and reduce velocity; o Treat water quality; and o Promote infiltrate and evapotranspiration of runoff. • Provide for appropriate conveyance to retention or detention storage facilities as needed for flows from large storm events. • Maintain open space functions consistent with common area uses (passive recreation, on-site sewage management, scenic vistas, etc). Refine the site design and layout to optimize the cumulative benefits of the natural hydrologic features, the constructed stormwater management system, and the land development components to achieve the minimum post-construction runoff volume, peak discharge rates and pollutant loads from the proposed land development site. Apply site design techniques and practices as appropriate based on: • Conservation Design principles and practices. • Sustainable Design principles and practices. • Low Impact Development Design principles and practices. Numerous practices and strategies can be considered where their aim is to sustain and utilize the benefits of existing site hydrology and minimize the generation of new stormwater runoff. Following are brief descriptions of various practices that can be used to achieve the principles of the natural hydrology site design process.

Design Process. The first step in applying natural hydrology site design CD is to identify, delineate and assess the functions of all existing natural resources and natural and man-made constructed hydrologic features that: are located within the project site; will receive discharge from the project site; or, or may be impacted by runoff or disturbance from the proposed land development project. This includesThese include: • Streams, waterways, springs, wetlands, vernal pools, and water bodies; • Drainage patterns, conveyances conveyances, and discharge points; • Natural infiltration areas and patterns; • Areas of natural vegetation or woodlands that provide significant evapotranspiration, pollutant removal, bank stabilization, flow attenuation, or riparian buffer functions; • Floodplains; and • Other features that contribute to the overall hydrologic function and value of the site and its receiving streams. Once this inventory and assessment are completed, these identified resources and features are then prioritized for their ability to provide hydrologic function and performance for managing runoff from the proposed site improvements. Specifically, they should be prioritized as follows: • Those to be incorporated into the site design in a manner that provides for their protection from any disturbance or impact from the proposed land development; • Those to be protected from further disturbance or impact and for which the proposed land development will provide improvement to existing conditions; • Those that can be incorporated into and utilized as components of the overall site design in a manner that protects or improves their existing conditions while utilizing their hydrologic function (e.g.i.e., for infiltration, evapotranspiration, or reducing pollutant loads, runoff volume or peak discharge rates, etc.) to reduce the need for or size of constructed BMPs; and • Those that may be considered for alteration, disturbance disturbance, or removal. These prioritizations are then applied as the basis on which to begin the site design lay-out, grading, construction, and permanent ground cover designs to achieve the five (5) Design CD Principles outlined above. The following section describes just a few of the many design practices, methods and techniques that are available to achieve the landowner’s desired land development goals and the desired environmental efficiencies intended by natural hydrology site design. Table B.1 – Site Design Process Principles and Techniques Design Principles Design Techniques Minimize land disturbance – both surface and subsurface. • Maintain the natural soil structure and vegetative cover that are often critical components of maintaining the hydrologic functions of natural infiltration, bioretention, flow attenuation, evapotranspiration, and pollutant removal. • Protect, or improve, natural resources to reduce the needs for environmental mitigation, future environmental restoration, and cumulative flow and water quality impacts of unnecessary disturbances within the watershed system. • Minimize the disturbance of natural surface and groundwater drainage features and patterns, discharge points and flow characteristics, natural infiltration and evapotranspiration patterns and characteristics, natural stream channel stability, and floodplain conveyance, etc. Minimize the cumulative area to be covered by impervious and compacted surfaces. • Minimize the size of individual impervious surfaces. • Separate large impervious surfaces into smaller components. • Disconnect runoff from one impervious surface to another. • Avoid unnecessary impervious surfaces. • Utilize porous materials where suited in lieu of impervious materials. Designing to the land, so that the layout of constructed and landscape features utilizes the natural topography and minimizes grading. • Prioritize on-site hydrologic features (i.e., for protection, improvement, utilization, or alteration) and natural site drainage patterns and infiltration characteristics and consider them for the cornerstones of the conceptual site design. • Reduce grading and compaction by applying selective grading design methods to provide final grading patterns tthat preserve existing topography where it most benefits natural hydrologic functions and where needed; this results in graded areas that evenly distribute runoff and minimize concentrated runoff flows. • Consider the scale and placement of buildings and other infrastructure to minimize impact to natural hydrologic features. • Incorporate unique natural, scenic, and historic site features into the configuration of the development, and ensure flexibility in development design to meet community needs for complimentary and aesthetically pleasing development, such as can be achieved through Conservation Design and Sustainable Design approaches. Design Principles Design Techniques Design the constructed stormwater management system to take advantage of the natural hydrologic landscape to achieve the required stormwater runoff control standards. • Incorporate natural hydrologic features that have been selected for their available capacity and function into the overall system of site runoff controls. • Incorporate Low Impact Development (or similar) BMPs and distribute storm flows to: o Reduce runoff; o Manage stormwater at or as close to the point of generation as possible; o Disconnect discharges from streets and municipal storm sewer systems; and o Select and design BMPs to give first priority to nonstructural and vegetation (landscape-based) BMPs, second priority to surface structural BMPs, third priority to subsurface structural BMPs, and design subsurface BMPs as shallow as possible. • Provide open channel conveyance, as needed, to: o Treat water quality; o Reduce runoff velocity; and o Promote infiltratation and evapotranspiration of runoff. • Manage remaining conveyed stormwater from small storms in common open space areas to achieve multiple objectives: o Disperse storm flows and reduce velocity; o Treat water quality; and o Promote infiltrate and evapotranspiration of runoff. • Provide for appropriate conveyance to retention or detention storage facilities as needed for flows from large storm events. • Maintain open space functions consistent with common area uses (passive recreation, on-site sewage management, scenic vistas, etc). Refine the site design and layout to optimize the cumulative benefits of the natural hydrologic features, the constructed stormwater management system, and the land development components to achieve the minimum post-construction runoff volume, peak discharge rates and pollutant loads from the proposed land development site. Apply site design techniques and practices as appropriate based on: • Conservation Design principles and practices. • Sustainable Design principles and practices. • Low Impact Development Design principles and practices. Numerous practices and strategies can be considered where their aim is to sustain and utilize the benefits of existing site hydrology and minimize the generation of new stormwater runoff. Following are brief descriptions of various practices that can be used to achieve the principles of the natural hydrology site design process.