maintaining rain gardens, swales, and stormwater planters
TRANSCRIPT
Maintaining Rain Gardens, Swales, and Stormwater Planters
Gail Shaloum, PLA BuildRight Conference April 2021
Agenda1. What is stormwater/why
manage it?
2. Legal background and local requirements
3. Understanding types of facilities and their components
4. Preparation, access, & safety
5. Maintenance:• Trash
• VegetationEffective plant choices
Weeds
Pruning
Replacement
• Irrigation
• Soils, erosion and sedimentation
• Structures
• Spills
6. Take-home messages
What is stormwaterand why manage it?
Image credit: https://www.hemetca.gov/898/Stormwater-Program
Stormwater impacts• Degrades stream
habitat
• Flooding
• Carries pollutants• Sediments
• Nutrients
• Metals
• Oils & Grease
• Pesticides
• Temperature
Why care about water quality?
5
Rain gardens, swales, stormwater plantersWhat’s the point?
1. Manage runoff at the source
2. Plants and soil slow, filter, infiltrate
3. Simple, low-cost, aesthetic
How do they work?
Legal background
Click to edit master
title style
Click to edit master subtitle style
Local requirements
• Maintenance agreements
• Inspections
• Reporting
Types of facilities and their componentsWATER INFLOW SLOWS,
POLLUTION FILTERED,SEDIMENT DROPS OUT
WATER OUT(or not)
Click to edit master
title style
Click to edit master subtitle style
Rain Garden with and without underdrain
-a bowl-shaped, generally flat-bottomed garden bed that collects and treats
stormwater runoff from impervious surfaces.
Rain Garden-Residential
Photo: East Multnomah Soil & Water Conservation District
Rain Garden-Municipal
Planted landscape facility designed to collect and absorb runoff and filter out
pollutants.
Swales (aka Bioswales)
Vegetated, open channel that carries, slows stormwater and filters out pollutants.
Photo: East Multnomah Soil & Water Conservation District
Stormwater Planter
“rain garden in a box”
Structural landscape reservoir
designed to filter out pollutants,
and in some cases, infiltrate
stormwater.
Click to edit master
title style
Click to edit master subtitle style
Anatomy of an infiltration planter
Graphic: Clean Water Services,
LIDA Manual
Click to edit master
title style
Click to edit master subtitle style
Anatomy of a flow-through planter
Graphic: Clean Water Services,
LIDA Manual
Stormwater Planter-forebay
RIP RAP
FOREBAY
Preparation-before you go
• O&M manual
• Maintenance plan or agreement
• As-built drawings/report
• Records from past maintenance visits
• Know what to expect
When you arrive: access
• How will you access?
• Flat or evenly sloped
• If fenced, trim fenceline for 3 feet if space allows
• Consider safety before you begin (do not enter flooded facility)
Safety
Personal Protective Equipment (PPE)
• Sturdy boots
• Gloves, puncture resistant gloves
• Ear plugs/earmuffs if operating power equipment
• Eye protection when “weed wacking” or mechanical trimming, handling large branches
• Long sleeved shirts and pants
• Hard hat if cutting
overhead
• *NEW FOR PANDEMIC: Face covering!
Maintenance: Trash and Debris Removal
• Remove trash and dispose appropriately.
• Remove accumulated debris.
Clogged inlets
City of Portland Environmental Services
Clogged outlets
City of Portland Environmental Services
24
Vegetation
Planting Zones
Different plants will thrive in different areas of the facility.
• Characteristics of suitable plants:• Not invasive
• Native vs. Non-native
• Water needs
• Potential for growth
• Refer to the jurisdiction’s list of recommended plants
Recommended Plants
Rushes & Sedges
WES SWML
Herbaceous - Plant ID
• Great for Bottom of Basin• Grass-like, but not...
Rushes are Round - Sedges have Edges
Rush (Juncus) Sedge (Carex)
Gerry Carr botany.hawaii.edu/Gerry Carr botany.hawaii.edu/
Rush: Solid, round stem
Sedge: Solid, triangular stem
Grass: Hollow, round, jointed stem
EMSWCD emswcd.org
John Ruter, University of Georgia, Bugwood.org
Effective plant choices-need another class!
Blossom
Weed Control
• What is a weed?
• Control strategies:• Least impact on
environment
• Prevent seeding
• Manual
• Herbicides
• PNW Weed Management Handbook:
http://pnwhandbooks.org/weedBlossom
Weed Control
• Pay attention to the roots & seeds
• Timing is important! Know when they can be best controlled
• Proper disposal
Blossom
Herbicide Use
• Use only as a last resort
• When is it necessary?
• What are the local regulations?• May be site and
plant specific
Yellow Flag Iris in a facility
Clackamas SWCD
Weed i.d. & treatment-need another class!
Vegetation: how much pruning?
Vegetation: replanting
Irrigation
• Plants are critical to the function of these facilities
• Irrigation essential for plant establishment & health
• At least 2 years, longer for high exposure areas
• Water a little less each year until plants established
How to irrigate
• Water should percolate into the soils and not run off the surface.
• Hand watering- Put as much down as possible until water begins to migrate along surface. Then go to the next plant.
• Don’t over-water.
• Drip irrigation is very effective.
Soils, Erosion and sedimentation
• Healthy soils hold water
• Plants, soils, microbes work together to capture pollutants
• Too much sediment will clog the system
• Compaction will clog the system
City of Portland Environmental ServicesExample of forebay doing its job
Erosion
Maria Cahill
When do You Need to Remove Sediment ?
• 2-3 inches of sediment• draw-down rates exceed about 36 hours• Don’t let things get out of control
City of Portland Environmental ServicesCity of Portland Environmental Services
Structures-Remove sediment & debris
Structures-check & clean, repair, or replace
• Underdrains
• Retaining walls
• Culverts
• Curbs
• Check dams
• Etc.
Spills
• Determine what type of material has spilled
• Block stormwater inlets
• Use absorbent material to contain the spill
• Remove contaminated soil from facility
• Protective gear for workers
• Contact owner, local emergency response, & OR Emergency Response 800-452-0311
Click to edit master
title style
Click to edit master subtitle style
Take-home messages
• These recommendations are general guidelines
• Check with the local jurisdiction for specific guidance
• Consult the Field Guide that was developed for our region https://emswcd.org/wp-content/uploads/2013/10/FieldGuideFinal.pdf
• For more information, contact: Gail Shaloum [email protected]