Difference between revisions of "Construction: pretreatment and inlet"

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(Created page with "Pre-treatment structures are most cost effective when they slow down incoming flows, collect sediment for easy clean out, and slowly release water to the bioretention facility mitigating erosion. Pretreatment structures/strategies can include curb cuts, Aggregates, proprietary devices like filters or hydrodynamic separators, vegetation, concrete sumps, membrane filters, overland flow sumps, etc. '''Construction Steps:''' *Installation of pre-treatment fea...")
 
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*Aggregate: Follow the guidance shown above in the section “Stone reservoir”.
*Aggregate: Follow the guidance shown above in the section “Stone reservoir”.
<gallery mode="packed" widths=300px heights=300px>
<gallery mode="packed" widths=300px heights=300px>
IMG_0891.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
IMG_0891.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden. (Photo Source: CVC, 2021)
IMG_0744.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
IMG_0744.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden. (Photo Source: CVC, 2021)
IMG_0788-1.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
IMG_0788-1.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden. (Photo Source: CVC, 2021)
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</gallery>



Revision as of 15:18, 22 September 2022

Pre-treatment structures are most cost effective when they slow down incoming flows, collect sediment for easy clean out, and slowly release water to the bioretention facility mitigating erosion. Pretreatment structures/strategies can include curb cuts, Aggregates, proprietary devices like filters or hydrodynamic separators, vegetation, concrete sumps, membrane filters, overland flow sumps, etc.

Construction Steps:

  • Installation of pre-treatment features will vary based upon type. Similarly, installation timeline will range with type and could occur at excavation and mass grading, curb work or at finishing grade. Given pre-treatment features are typically integrated with the LID inlet coordination amongst multiple sub-contractors is sometime needed. The following details steps for various pre-treatment types:
  • Vegetation: Follow the guidance shown below in the section “Plant Material Verification and Installation”
  • Curbing: Follow the guidance shown above in the section “Curbing”.
  • Aggregate: Follow the guidance shown above in the section “Stone reservoir”.
  • Proprietary pre-treatment device:
  1. Excavate and prepare base for proprietary pre-treatment device according to design.
  2. Install proprietary pre-treatment device according manufacturer directions.
  3. Manufacturer representative may need to confirm proper installation and functioning through approved testing and inspection.

Key Inspection Points:

  • Verify that the correct pre-treatment device (jellyfish filter, vegetation, curbing, etc.) is being installed.
  • Verify that all components of the pre-treatment device are installed
  • Verify correct size and location of pre-treatment device.
  • Verify correct elevation, slope, and footing according to design
  • Is it tied into the curb, downspout, or other inlet? Or could happen before the curbing?
  • Wet weather performance check:
    • Does it work?
    • Is water entering the LID facility properly?
    • Is sediment and debris accumulating?
    • Is it dissipating erosive forces?

Mistakes to Avoid:

  • Pre-treatment component parts are missing
  • Grading/elevation errors that deviates from design
    • Incorrect pipe inverts causing short circuiting
    • Insufficient grade drop or slope into pre-treatment to ensure positive flow of water
    • Improper grading from pre-treatment to LID feature inhibiting positive flow
    • Insufficient sump depth to account for sediment and debris accumulation
  • Using wrong concrete forms if concrete curbs are part of pre-treatment.

For more information about pre-treatment strategies and their design, visit these page: Pretreatment and Pretreatment features.