Category Archives: Technical Information

Meeting the 2016 Seattle Stormwater Code

seattle-1027254_640The new Seattle 2016 stormwater code, effective Jan 1, 2016 addresses stormwater regulations in order to protect people, property, and the environment from damage caused by stormwater runoff. Drainage control, flow control and stormwater treatment, and “On Site Stormwater Management”,  are key factors in what you can and cannot do with runoff caused by impervious surfaces. The new code satisfies Seattle’s obligation to be in compliance with the Municipal Stormwater Discharge National Pollutant Discharge Elimination System (NPDES) Permit, issued by the Washington State Department of Ecology.

The city of Seattle has put out new publication of “Best Management Practices.” The Primary purpose of the BMPs is to protect beneficial uses of water resources, while reducing erosion, and contamination of stormwater runoff entering our waterways. Collecting rainwater for beneficial use can have a significant effect meeting the requirements of the new stormwater codes on any new construction within city limits. Collecting the rain and using it reduces the impervious surface of your project. Whether its use is for irrigation, toilet flushing, laundry facility, or potable use for residential, adding rainwater collection to your project’s design can be the answer to “what do I do with the runoff to meet these challenges?”, to comply with the new stormwater code.”

Contain Water Systems Inc. and RainBank Rainwater Systems can help your Seattle building project meet the 2016 stormwater code requirements.

Contain Steel  Water Tanks can be an integral part of design for commercial construction in reducing costs due to the new code and its requirements. RainBank Rainwater Systems has been designing and installing systems for more than 15 years in Washington State. Whether your project is commercial or residential, potable or non potable, RainBank and Contain have the answers for your next project. We work closely with architects, engineers, contractors, and most importantly, the customer to help meet the new stormwater codes with a knowledgeable staff and commitment of your project.

Considerations for Water Treatment

FiltrationRainBank Rainwater Systems designs and installs custom treatment systems to meet customers’ specific needs.

Harmful bacteria, pathogens, and cysts removal is a must in a potable rainwater collection disinfection train. This is typically achieved with a class “A” UV light. Flow rates are calculated to achieve the correct amount of contact time with the UV spectrum for proper disinfection. The correct class of UV for a specific application is required. A class “A” UV must be used for water that is not deemed safe to drink. A class “B” is only used for water that has already been safe to drink.

But there are other considerations for water treatment. The raw water must be relatively free of sediments, turbidity, organics and inorganics before entering the UV chamber. The UV spectrum will not be able to penetrate the water column effectively otherwise. Special consideration of environmental constituents should also be addressed for proper treatment.

Environmental concerns can include location of collection area. Where is the house located?  Possible hydrocarbons Skagit_Filtrationfrom a nearby freeway would be a concern. Pesticide use from farming or city landscaping maintenance should be considered. Roof material and manufacturing process could pose a health threat and should be addressed – all of which can be corrected with proper filtration, whether it is accomplished with canister elements or back flush devices.

Rainwater is typically acidic, approximately 5.5 to 6.0 ph; nominal being 7.0 ph. The lower ph levels, while not considered harmful to humans, can have a negative effect on plumbing and fixtures. A more nominal ph level can be achieved with proper treatment.

Rainwater is relatively clean to begin with; much more than surface water. It is what it comes in contact with that can change its purity. Proper design and installation of a filtration and disinfection only comes from using the “right tools for the job”.

Is Acid Rain a Concern in Rainwater Collection?

raindrop stock photoWhy worry about acid rain? pH level is a quantitative measure of hydrogen ions with a level of 7 being neutral. Anything less than 7 is considered acidic, with anything above 7 considered alkaline. In the Pacific Northwest pH of our rainwater is typically 5.5.

Drinking acidic rainwater is not normally a health concern, however lower pH levels can cause blue/green staining in sinks and tubs, and sometimes in severe cases, may cause leaching and damage to copper plumbing. Simple pH testing strips can indicate the pH levels in collected rainwater. Generally, the smallest amount of buffering can adjust levels to a nominal 7.0 , or neutral. Adding 4 ounces of baking soda in solution to every 1,000 gallons of stored rainwater is an effective method of adjusting pH. It is recommended to start with the minimal amount, then test again and increase if necessary.

Neutralizing filters typically contain calcium carbonate, which dissolves as it interacts with untreated water, increasing pH values to appropriate range through addition of neutralizing materials, increasing to 6.5 pH to 8.0 pH although spikes in hardness may incur. Chemical pumps can inject calcite into the water flow after filtration and are effective if placed upstream of the pressure tank or day tank.

It is advised that testing pH levels at the storage site, as well as at the tap be conducted before adjusting. Variables such as temperature and materials used in the water system itself can have effects on pH levels, so it is good to know where your baseline is. Sampling can be done by a lab for accuracy if required.

The key is to know, maintain, and service your rainwater collection system for best results.

Rain Drop Stock Photo courtesy of samuiblue /