Bioswales & Bioretention Areas in Portland, OR

When stormwater gathers on nonabsorbent surfaces like roofs, streets and sidewalks, it provides a vehicle for transporting pollutants such as metals, chemicals, debris and bacteria. While most residential and urban areas use sewer systems and storm drains to prevent pooling water, stormwater runoff is then channeled into nearby bodies of water such as lakes, rivers and oceans with these pollutants in tow. 

Alpha Environmental provides environmentally-friendly methods to manage stormwater runoff. We offer bioswales and bioretention basins that filter and slow the drainage of stormwater, allowing it to be properly treated before making its way into sensitive habitats. We also provide regular maintenance and annual check-up services to keep these systems working as designed.

Bioretention Basins

Bioretention areas are landscaped depressions or shallow basins that slow and treat stormwater on site. Common along roadways or in parking lot islands, bioretention basins mimic the ways in which pollutants are removed from forested areas by passing stormwater through layers of soil, mulch and plants that act as filters. The treated water is then directed to drains and/or surrounding bodies of water.

Bioretention areas are extremely useful in heavy rain conditions, as they often allow water to pool up to several feet before passing it through to an overflow outlet. This helps to prevent flooding.

Bioretention basins are typically composed of seven elements:

  • A grass buffer strip that reduces the speed of runoff stormwater and removes debris.
  • Vegetation that helps remove water through evaporation. Plants also remove excess nutrients through nutrient cycling.
  • A shallow ponding area that provides storage for excess stormwater and its subsequent evaporation. This area also aids in the settlement of solid and liquid debris. 
  • Mulch, which provides an organic layer that encourages the biological degradation of petroleum-based pollutants. Mulch also aids in filtering out pollutants and reduces soil erosion.
  • Engineered soils to support plant growth, increase nutrient uptake and provide water storage. These soils should include some clay to absorb pollutants such as hydrocarbons, heavy metals and nutrients.
  • A sand bed, which provides drainage, allows air into the planting soil and aids in flushing pollutants.
  • An underdrain system to channel excess treated stormwater to a storm drain system or nearby bodies of water.

Bioretention basins are perfect for small areas like residential neighborhoods or shopping centers, as they contribute to urban aesthetics while restoring natural water cycles.

Bioswales and Rain Gardens

Bioswales and rain gardens are vegetated, shallow, landscaped areas designed to capture, treat and infiltrate stormwater runoff as it moves downstream. While the two systems are similar, bioswales are designed to filter and carry stormwater to storm inlets or nearby waterways. In contrast, rain gardens are specifically designed to filter and absorb stormwater in place of redirecting it.

Bioswales and rain gardens should be composed of diverse, deep-rooted, native vegetation to increase the amount of time water spends in the area. The sides of these shallow areas should be slightly sloped to allow for the collection of stormwater.

These systems are often used in urban areas near cities or busy streets, where stormwater is more likely to collect on nonabsorbent surfaces, such as: 

  • Parking lots
  • Rooftops
  • Sidewalks
  • Driveways

Both bioswales and rain gardens are excellent for filtering water on a smaller scale. The majority of precipitation comes from small rain events, during which these systems can capture and filter nearly all of the resulting water.

Bioretention Systems in Portland, OR

Once installed, bioswales and bioretention areas require regular maintenance and annual checkups, just like regular storm drains and inlets. Contact us today to learn more about our environmentally friendly stormwater management systems!

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Why Choose Alpha Environmental

Our goal is to get the job done right while protecting our client. We are committed to ensuring you are safe in your residence, no matter what. We are fully licensed, bonded, insured, and here to help with all of your environmental needs.

Family Owned & Operated

We pride ourselves on strong company values that translate into service levels which go above and beyond average service providers

21+ Years Experience

For over two decades we've been doing the dirty work, serving residential and commercial customers in the greater Portland area

Care & Ownership

Our entire team is committed to ensuring your home or place of business is safe and every job gets done the right way

David D.
Lake Oswego, OR
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My wife and I experienced a hot water pipe busting in the crawlspace. It has been a total nightmare. However, Chris and his team provided expert quality care, with timeliness and the greatest degree of professionalism. I would HIGHLY recommend Alpha Enviornmental!
Zhanna S.
Beaverton, OR
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Can’t say enough about Alpha Environmental! Their costumer service is 10/10, they have really good systems in place, responsive, and professional. The gals in the scheduling department are always so kind! As a real estate agent, I use Alpha’s services numerous times a year. Either it’s for Mold bids, oil tank decommissioning, radon etc. They always do a fantastic job! Thank you for all the work you do!
Kristen L.
Portland, OR
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Wow where do I even begin?? We’re absolutely thrilled by the work Alpha has done for us and we’re eternally grateful to them for ridding our house of asbestos tile! They’re polite, kind, professional — from estimator Filo to manager Dame to Jake, Melvin and the other two guys on the crew (so sorry we didn’t get your names) — you guys are awesome and we so appreciate your help. Our house looks amazing. The peace of mind you’ve given us is priceless. We can’t thank you enough. We’ll certainly be in back in touch if we ever need any of your services again. Thank you thank you!!!
Jeff S.
Salem, OR
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Alpha environmental's employees were punctual, pleasant to work with and there services are reasonably priced. I highly recommend them because I would use them again in the future.
Lea C.
Tualatin, OR
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Took a water sample in for lead testing and they were so fast and helpful. Rodolfo was so nice and informative in explaining the testing and what it meant! Would definitely recommend everyone to go there and will go to them for any future needs!
Claire B.
Portland, OR
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Alpha environmental was extremely helpful in navigating me through the process of testing some leftover construction debris for asbestos so I could take it to the dump. Their office manager spent time with me on the phone discussing the options for sample collection, and was extremely friendly in answering my many questions. Sample drop off at the office was easy and the results even came back a few days earlier than expected. Will definitely return if I need more sampling done!
Jeff C.
Tigard, OR
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I would highly recommend anyone wanting, quick efficient services relating to environmental testing to check out Alpha Environmental. Not only was the staff friendly and responsive, but also professional! If I could 6 stars out of 5, I would!
Jotham P.
Portland, OR
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We used Alpha Environmental Services to conduct our home inspection, radon testing, sewer scope and oil tank decommissioning. Every part of their service was really professional. They took so many great photos of the house during the inspection and offered lots of explanation on what they found. Great team. Highly recommend!

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A trusted member of our team will reach out within 1 business day to schedule