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Do You Need In a Local Stormwater Manual?
The stormwater manual
guides local engineers so that they can comply with the stormwater requirements
prescribed in the local stormwater ordinance. A good manual contains specific
guidance on how to select, size, design, construct, and maintain practices
at each development site. A typical manual will contain the following elements:
The manual will typically detail the legal requirements as set forth in
the Stormwater Ordinance.
The manual needs to identify minimum sizing criteria for practices to meet
groundwater recharge, water quality, channel protection, and flood control
of Acceptable Practices
The manual should include a list of practices that can meet water quality
requirements. An engineer can choose from this menu of practices to treat
stormwater runoff from a new development.
Criteria The performance criteria provide required minimum elements and guidance
to ensure that practices are designed and maintained to ensure practice
longevity and performance.
on STP Selection
This section presents criteria to guide the design engineer to select the
best practice for the site, based on characteristics such as soil type,
site slope, and the local watershed conditions.
Credits Stormwater credits are reductions in stormwater volume requirements
given in exchange for incorporating site design techniques that minimize
the need for STPs on the site. Many manuals do not incorporate credits,
because they can increase the burden of review on local governments substantially.
Examples Design examples step the engineer through designs for a representative
group of STP design variations. They should illustrate how to select, size,
and locate the practice on the site.
Specifications Construction specifications detail specific materials and construction
standards that ensure that the practice will function as designed.
Manual Builder provides a toolbox for developing a stormwater treatment practice
(STP) design manual. It includes STP design and construction criteria and
provides schematics and graphics for each practice. It also provides information
about maintenance requirements and the typical local review process for STP
design and construction. Each manual needs to be customized to meet the needs
of the community where it is being applied. As a result, the manual builder
does not prescribe one specific set of criteria, but instead presents a series
of options for stormwater managers to choose from. Key decision points for
the stormwater manager are identified with this symbol: