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Soils Well-designed systems capture sediment near the entrances Sediment loads vary by facility Regular visual checks are the key City of Portland Environmental.

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Presentation on theme: "Soils Well-designed systems capture sediment near the entrances Sediment loads vary by facility Regular visual checks are the key City of Portland Environmental."— Presentation transcript:

1 Soils Well-designed systems capture sediment near the entrances Sediment loads vary by facility Regular visual checks are the key City of Portland Environmental Services

2 Soils City of Portland Environmental Services

3 Soils Visit the facility at least twice a winter after big storms Check sediment accumulations as you’re doing routine maintenance Monitor draw-down rates – how long does it take for standing water to disappear after the end of a storm ? Make notes for future reference

4 Plants and sediment can reduce depth EMSWCD

5 When do You Need to Remove Sediment ? If 2-3 inches of sediment accumulates When draw- down rates exceed about 36 hours Don’t let things get out of control (photo) City of Portland Environmental Services

6 When do You Need to Remove Sediment ? City of Portland Environmental Services

7 Soils: Removing Sediment Schedule all maintenance for dry weather unless there’s an emergency Rakes and shovels (hand removal) are best to avoid damaging the plants Be sure to loosen the underlying native soil If large equipment is needed avoid compacting the soils If slow infiltration rates persist, remove the top couple of inches of soil

8 When to Be Concerned…. Nccwep.org Petroleum sheen Foul smell Morguefile

9 Soils: Sediment and Soil Disposal Check for evidence of contamination: color and smell In most cases stormwater sediment is not hazardous and can be disposed of as solid waste. Places to be concerned: recycling facilities, fueling stations, industrial storage areas, etc. If you have questions, contact DEQ at Or consult DEQ’s guidelines for hazardous waste at

10 Mulch Suppresses weeds and maintains soil moisture Is a surface for deposition of sediment (for easy sediment removal) Apply 2-3 inches after planting, after removing sediment, and any time there are bare spots Common mulches: medium hemlock,yard- debris compost. Gravel “mulch” is sometimes used at entrances Green Girl Land Development Solutions

11 Mulch Mulch sometimes floats in the first storms just after construction. Yard debris compost is less prone to floating, but it can be a source of weeds Many LID systems are densely planted and need only spot- mulching after the first couple of years Green Girl LDS

12 Do’s and Don’ts Do Visually monitor the facility on a regular basis Remove sediment when it reaches 2-3 inches Plan to take action if drawdown times exceed 36 hours Mulch and plant bare spots for erosion control Loosen the soil after removing sediment Don’t Compact the soils by working in the facilities when the soils are wet (wait until summer) Assume a facility is permanently clogged until steps have been taken to remove sediment layers Handle soils that smell or look odd (contamination)

13 Structures Prevent Erosion Rip rap vs. no erosion prevention Green Girl LDS

14 Structures Remove Sediment & Debris Rip rap Green Girl LDS

15 Structures Remove Sediment & Debris Shallow forebay Green Girl LDS

16 Structures Remove Sediment & Debris Forebay with sump Green Girl LDS

17 Structures Remove Sediment & Debris Curb cuts Green Girl LDS

18 Structures Remove Sediment & Debris Flat outlets vs. beehive outlets Green Girl LDS

19 Structures Prevent Excessive Ponding Under drains Green Girl LDS

20 Structures Prevent Excessive Ponding & Flooding Overflows

21 Structures Prevent Flooding Obstructions

22 Structures Protect Structural Integrity Curb damage

23 Structures Protect Structural Integrity Walls Green Girl LDS

24 Structures Protect Structural Integrity Keystone Retaining Walls


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