19 Apr BlueGold Part 3: From Plans to Flow – Demystifying Austin Urban Residential Rainwater Harvesting

This is part three of a three part series by Sara Earl of Blue Gold Engineering, a water and wastewater firm with a division offering design/permit/build for residential rainwater harvesting, stormwater irrigation and greywater reuse systems.

I’ve covered some basic rainwater harvesting information including “why’s” and design considerations in Part One and Part Two of this series. This final entry is an overview of the City of Austin’s rebate rules and applicable building regulations folded in with important steps in the installation process.

Very simply stated, the city’s primary concern when you install a rainwater harvesting system is back flow of your rainwater into the city’s water supply. Thus, the installation of a rainwater harvesting system will necessitate compliance with the city’s development codes.

The very first thing you need to do is get a rainwater rebate approval from the city before you purchase your tank or any other equipment. Otherwise you will not get a rebate. The rebate application requires preliminary sizing and drawings. The rebate only counts towards the downspouts, first flush diverter or roof washer, conveyance and tank, in other words, not gutters or any irrigation purchases. Once your application is approved you have 90 days to finish everything and submit receipts along with the rebate submittal form.

If you’re installing a gravity fed system with a tank that’s 5,000 gallons or less, then you won’t need any further permits or inspections from the city, although Austin Water (the rebate people) may elect to inspect your finished project.

If your future system will store over 5,000 gallons, it will trigger the need for a building permit, which, in turn, triggers several other steps. Any tree over 19” in diameter must be noted on building permit drawings, protected appropriately and inspected by the City Arborist’s office prior to construction. You’ll need to request and submit a site plan exemption along with the building permit. Austin Energy must approve your site plan exemption drawings before the city will review the building permit. While each application requires it’s own kind of drawings, the building permit application requires the most specific and detailed drawings. To save time, money and effort, we generally do a final set of plans and use them for all applications.

Plumbing, electrical and irrigation permits must be pulled and then construction can finally begin! The work must be performed by a city-approved master plumber, master electrician and the irrigation installer must be licensed by the Texas Commission on Environmental Quality (TCEQ). Once all these systems are installed, the city will want to do an initial inspection before components are covered with earth. They’ll all come back and do a final inspection when you’re done. An approved final inspection results in an approved permit.

A city-approved inspector will need to specifically inspect your Reduced Pressure Zone (RPZ) Valve. A Customer Service Inspection (CSI) is another third party inspection which verifies there is no back flow of rainwater into the city’s supply. A CSI is required annually by the city. Austin Water may elect to do a final inspection before approving the release of rebate funds.

You might want to have some idea of regular maintenance that your rainwater harvesting system will require. After every period of rain you’ll need to drain the first flush diverter, or roof washer, and conveyance. You should always be on the lookout for leaks and rust. The leaf screens, downspout(s) and tank roof will need to be cleaned regularly and you should recirculate the rainwater with the pump while you’re at it. Cut any tree branches away from the roof and watch your vegetation for evidence that the irrigation system is not working (uneven growth, overly-wet soil) seasonally. You should test any electrical components including the irrigation system controls and pump annually as well as order the city-mandated annual CSI inspection.

For further information, check out the Texas Water Development Board’s Manual of Rainwater Harvesting, posted here: http://www.twdb.state.tx.us/innovativewater/rainwater/docs.asp (look for a link to the PDF under Manuals).

Why you would want to hire an engineer? At Blue Gold Engineering, our “resource balanced design” process delivers the most sustainable and cost-effective solution for your lifestyle, structure and site. Our experience guarantees approved applications and permits to fast-track you through the city’s process. Orchestration of an experienced staff and pre-qualified subcontractors includes managing bid collection, quality control and oversight of all inspections (up to 10!). We create professional construction plans and specifications and personalized operations and maintenance instructions. For more information about Blue Gold Engineering, please see our web site at www.bluegoldengineering.biz or call us at 512.944.0677.
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SARA EARL, C.E.O.
512-809-5709
sara@bluegoldengineering.biz
www.bluegoldengineering.biz