The Stormwater Blog 

System hydraulics refers to how water flows through a stormwater filtration system. The following three steps should be part of the hydraulics evaluation process:

Perhaps the most recognized Low Impact Development technique, bioretention, incorporates landscaped features to slowly percolate stormwater runoff through plants and engineered soil prior to infiltrating that water into native soils.

As a state storm water regulator, I see many storm water plans. These plans detail everything that would be done to protect water quality and prevent erosion. Yet even a well-written and well-executed BMP plan will not provide the intended service without proper maintenance. 

Common infiltration practices include drywells, bioretention, permeable pavement, infiltration trenches, infiltration basins, and subsurface infiltration galleries. Regardless of their form, all infiltration systems have three primary components: storage, treatment, and infiltration.

The City of Los Angeles Bureau of Sanitation received the Outstanding Stormwater Best Management Practice (BMP) Implementation Award for its Garvanza Park Stormwater BMP Project from the California Stormwater Quality Association (CASQA). 

Drafting stormwater regulations that are clear, comprehensive and effective is crucial to protecting and preserving receiving waters.  The Clean Water Act has yielded a wide spectrum of local stormwater regulations and policies, but many leave something to be desired when it comes to actually mitigating the impacts of urban runoff.  It has been our experience that many local regulations are missing core components that are invaluable in achieving our ultimate goal.

When you mention a commercial rainwater harvesting system (RWH) to an engineer, developer or owner, one of the first questions you get is “what’s the ROI?” Return on Investment and Net Present Value vary widely depending on specific project variables and there is no one correct answer.  The three largest factors impacting ROI are initial cost of the system, water utility savings, and the value of land space saved for a stormwater BMP.

Mother Nature’s soil is the best of all urban stormwater Best Management Practices (BMPs). Soil infiltrates precipitation, reduces runoff, filters and captures most pollutants, recharges groundwater, and maintains a diverse, self-sustaining biological community.

Historically, underground infiltration beds have been laid out in either square or rectangular shapes, sometimes far away from where the actual rain drops fall. These large systems are typically fed by a series of upstream catch basins and conveyance pipes. Several factors contribute to site layout, but mostly it simplifies the hydrologic and hydraulic modeling process, and keeps infiltration beds away from more sensitive underground infrastructure.

The low impact development (LID) movement seeks to provide solutions that reduce impervious area and restore predevelopment hydrology. It is understood that small storms (with a frequency less than 6 months) are responsible for most annual urban runoff and groundwater recharge, and LID facilities are designed to reduce the volume and peak rate of the urban runoff from these small storm events using small-scale, engineered on-site hydrologic controls featuring natural components.