GSI_MX_Guide_v1_2022.pdf
PDF 11 MB Posted
- Attached to
- Qualified Vendor List (QVL) for Green Stormwater Infrastructure (GSI) Landscape Maintenance
- Solicitation number
- 250123
- Issued by
- Pima County, Tucson City, Arizona
About this file
This is a Green Stormwater Infrastructure (GSI) Maintenance Guide published by the City of Tucson Water's Storm to Shade Program in August 2022, serving as a pocket guide for landscape professionals and maintenance personnel working on GSI assets throughout the city. The guide establishes best practices and procedures for maintaining GSI features, which are landscape elements designed to capture and use stormwater runoff to support healthy soil, vegetation, and biodiversity. GSI assets include inlets, outlets, overflows, basins, berms, swales, and associated vegetation located on public property. The guide covers seven key maintenance areas: introduction to GSI and its benefits, structural components of GSI features, maintenance tools and quick reference guides, plant care protocols, soil and mulch management, tree pruning standards, and seasonal maintenance checklists. The maintenance approach emphasizes minimal intervention philosophy, prioritizing natural processes while ensuring functionality of assets, with routine maintenance tasks including removal of obstructions from inlets and outlets, accumulated sediment removal, invasive weed and trash removal, safety-based pruning, and minor rockwork repair.
The guide provides comprehensive technical guidance on plant health maintenance, including irrigation assessment and repair, dead plant replacement, mulch layer preservation, and weed removal techniques using the "Chop and Drop" method for organic material retention. Tree pruning guidance specifies that pruning should only occur for safety concerns, clearance issues, or tree health, with certified arborists required for significant pruning work. Sight visibility triangle clearance at intersections requires 7-foot tree pruning and 30-inch maximum shrub heights. The guide identifies common invasive weeds including stinknet, buffelgrass, fountain grass, goat head, Russian thistle, London rocket, cheeseweed, and bermuda grass, with notes on fire risk concerns. Seasonal maintenance checklists are provided for winter (December 1–February 15), late winter/early spring (February 16–March 31), spring/pre-monsoon (April 1–May 31), summer/monsoon (June 1–August 31), and fall/post-monsoon (September 1–November 30) periods. The guide references the City of Tucson Landscape Maintenance Manual and provides contact information for the Storm to Shade Program and partner organizations including Tucson Clean & Beautiful and the Pima County Flood Control District.
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Text version
Green Stormwater Infrastructure (GSI)
Maintenance
Published by the City of Tucson Storm to Shade Program
First Edition: August 2022 A Pocket Guide
Contents Intro to GSI / what is it and why is it important?
The Structure of GSI / what’s in your basin?
GSI Maintenance / common tools, quick GSI maintenance guide
Plant Care for GSI / plant care checklist, common weeds
Soil and Mulch / benefits and guidelines
Tree Care for GSI / basic tree pruning guide
GSI Maintenance by the Season / checklist
Common GSI Features:
The Storm to Shade Program administered by Tucson Water funds and oversees the maintenance of GSI features located on public property in the City of Tucson. This manual provides an overview of best practices for maintaining GSI features and is a guide for landscape professionals and anyone else working in GSI.
Chicane / Curb Extension Traffic Median
So what is green stormwater infrastructure (GSI) and why is it important?
GSI refers to landscape features designed to capture and use stormwater runoff from hardscape to support healthy soil, vegetation, and biodiversity.
GSI includes inlets, outlets, and overflows as well as earthworks such as basins, berms, and swales to capture, contain, and direct the flow of water into vegetated areas. GSI provides a variety of benefits including...
Reducing stormwater pollution and improving water quality
Shading and cooling streets, sidewalks, bikeways, and parking areas
Mitigating minor flooding
Creating wildlife habitat and supporting biodiversity
Beautifying the urban environment
Providing a nature based complement to gray infrastructure
Decreasing reliance on potable water for landscape irrigation
Right-of-Way BasinTraffic Circle
The structural elements of GSI
INFILTRATION BASIN
CURB CORE
INLETS/OUTLETS
PLANTING SHELF
SEDIMENT TRAP
CURB CUT
Depression within a GSI feature that allows stormwater to infiltrate the soil
Circular core drilled through curbing that serves as an inlet or outlet
Conveyance allowing stormwater to flow into or out of a GSI feature
Elevated planting area within a GSI feature ph ot o:
T uc so n Cl ea n
B ea ut ifu l ph ot o:
W at er sh ed
M gm t G ro up
Rough area at inlet that allows sediment to settle before water enters a basin
Removed section of curbing that serves as an inlet or outlet
GSI Maintenance the tools of the trade plant ID appsbypass pruners plant ID guides tool disinfectant tree pruning handsaw flat shovel round shovel digging barleaf rake pitchfork push broom trash grabber geologist hammer gloves safety glasses
Cues to Care... quick GSI maintenance guide
Can stormwater easily enter and collect in the
GSI?
1. 2.
Is vegetation obstructing signage or visibility or impeding pedestrian or vehicle traffic?
YES NO
YES
YES
NO
no action required no action required
Remove obstructions (debris, rocks, sediment, vegetation) and dispose of or redistribute appropriately*.
no action required
Remove sediment from the bottom of the infiltration basin.
Dispose of/redistribute removed material appropriately. Mulch exposed soil whenever possible.
Are there obstructions to the inlet and/or sediment trap?
Perform the minimum pruning necessary to remove obstructive or dangerous vegetation. Do not perform significant pruning or tree removal without consulting an ISA certified arborist.
See GSI Pruning Guide
Is the ground/soil level at the bottom of the infiltration basin lower than the level of the inlet?
NO YES
NO
* Redistribute excess sediment to high points of GSI or carry off site.
3. 4.
Is the GSI feature free of trash?
YES YESno action required no action required
Remove weeds, invasive plants, and volunteer trees** See Plant Care for GSI
Remove trash and dispose of it appropriately.
Reference Common Weeds or preferred plant guide
NO NO
UNSURE
Less is More: GSI uses natural processes to perform ecosystem services. Minimal interventions that ensure the function of the asset are often most appropriate for routine maintenance. Routine maintenance of GSI assets includes:
• Removing obstructions from inlets and outlets
• Removing accumulated sediment
• Removing weeds, invasive or unwanted plants, and trash
• Pruning for safety
• Minor rockwork repair, securing/replacing loose rock
• Leaving organic material onsite (no raking for aesthetic purposes)
** Volunteer trees that do not obstruct inlets or site visibility may remain
Is the GSI feature free of weeds, invasive plants, and unwanted volunteer trees?
Plant Care for GSI Plants are an integral part of GSI and offer a number of services and benefits including:
providing evaporative cooling through transpiration filtering and breaking down contaminants in stormwater runoff improving soil structure to facilitate infiltration and percolation providing habitat for wildlife providing shade, screening, and natural beauty
Plant health is crucial to the function of GSI features. Supporting plant health during routine GSI maintenance involves:
ensuring irrigation is functioning / plants are receiving water replacing dead plants minimizing pruning maintaining a mulch layer to conserve soil moisture
Remove weeds, invasive plant species, and unwanted volunteer trees by pulling or digging them out
Remove unnecessary tree stakes/nursery stakes, and girdling ties
Assess irrigation
| Check for and repair leaks |
| Look for where plants are missing but irrigation is |
still running Move irrigation away from established tree or shrub trunks to the edge of canopy
Clear rocks, sediment, and deep mulch away from the base of trunks
Expose buried root flares
Practice the “Chop and Drop” method, leaving leaf litter, seed-free weeds, and trimmings less than 1” diameter and 3” length in basin bottom as mulch
Trim back shrubs and other low-lying vegetation from walkways/roadways
| Prune only for visibility and clearance |
| Do not prune to artificially shape the plant !!! |
GSI Plant Care Checklist
Chop Free Mulch!& Drop
Sustaining Soil Maintaining healthy soil is also crucial to plant health and GSI feature functionality. Consider the following best practices while performing GSI maintenance:
minimize soil disturbance, avoid raking for aesthetic purposes keep soil mulched (wood chips, leaves, trimmings, other aggregates) avoid activities that can lead to soil compaction - i.e. driving, parking, walking in or on GSI features or plant root zones minimize erosion - ensure earthworks, rockwork and other grade controls are in place and functioning avoid the use of herbicides and pesticides*
Magical Mulch preserves soil moisture adds organic matter to soil reduces weeds and erosion supports microbial activity keeps soil cool
Covering the soil surface with 2” - 4” of mulch can provide these benefits and more.
* Herbicides/pesticides may be applied by AZ State Certified Applicators with formal approval from COT S2S program’s maintenance leadership.
Common Weeds
Stinknet fire risk fire risk fire risk fire risk fire risk
BuffelgrassBuffelgrass Fountain Grass
Goat Head
Russian Thistle London Rocket Cheeseweed
Bermuda Grass
GSI Tree Pruning Guide
Tree Pruning should only be done if there is a safety concern, clearance issue, or if the health of the tree is at stake. A certified arborist should perform any significant pruning. Every pruning cut is a wound the tree must seal and improper cuts or too many cuts endanger the life of the tree.
Sight Visibility Triangle (SVT) Clearance - At crosswalks and intersections, an unobstructed and continuous view of both the intersection and the intersecting roadway helps pedestrians, cyclists, and drivers avoid conflicts. Trees should be pruned to 7’ for SVT clearance and shrubs should not exceed 30” in height.
Right Tree Right Place - When planting or replacing trees, consider the tree’s mature size and growth form as it relates to the planting location. Selecting an appropriate tree can help to minimize pruning needs, clearance concerns, and damage to adjacent infrastructure.
30” sh ru b
SV
T cl ea ra nc e at i nt er se ct io ns ensure visibility of roadway signs
Pruning for Safety
• pedestrian clearance
• vehicle clearance
• visibility of roadway signage
• site visibility triangles
• to remove broken or hazardous limbs
Pruning for Tree Health
• removing dead wood
• removing rubbing or crossing branches
• removing codominant branching
• remedial pruning for improper pruning such as stub cuts
15’
7’ ve hi cl e cl ea ra nc e pe de st ria n
SV
T cl ea ra nc e clear tree limbs from bike lanes
Basic Tree Pruning the DOs cut 1 final cut cut 2
Prune as minimally as possible
Use the right tools - bypass pruners, tree pruning handsaw
Use clean tools - disinfect tools between each tree or shrub
Use proper pruning techniques :
Reduction Cuts (right) Trim back to the nearest lateral branch or to main trunk, ensure that the remaining lateral is at least 1/3 the diameter of the cut branch.
The 3 Cut Method (left) for large or heavy branches:
Cut 1 - Make an undercut through 1/3 of branch Cut 2 - Make the top cut slightly farther on the limb than the undercut to remove the branch Cut 3 - Make final cut just outside branch collar/branch bark ridge to remove the stub lateral branch
1/3 diameter of cut branch cut branch
Proper pruning techniques can prevent injuries to trees that make them susceptible to decay or infestation, or lead to a loss of photosynthetic function.
the DON’Ts stub flush cut
Don’t remove more than 1/3 of the canopy at once
Never ‘Top’ trees/shrubs or prune them into artificial shapes
No Stub Cuts
No ‘Topping’
No Flush Cuts
No ‘Lion Tailing’
Don’t remove anything that does not present a safety or visibility issue
Don’t prune trees that appear to be less than 2 yrs old
*Refer to City of Tucson Landscape Maintenance Manual (Nov 2020) for more detail
SPRING / PRE-MONSOON april 1 - may 31
SUMMER / MONSOON jun 1 - aug 31
FALL / POST-MONSOON sep 1 - nov 30
GSI Maintenance... a seasonal checklist
Clear inlets and outlets
Remove excess sediment
Prune for safety
Remove trash
Clear inlets and outlets
Remove excess sediment
Pull invasive weeds
Leave native annuals
Light pruning as necessary
Remove trash
Clear inlets and outlets
Remove excess sediment
Pull invasive weeds
Leave native annuals
Light pruning as necessary
Remove trash
LATE WINTER / EARLY SPRING feb 16 - mar 31 Clear inlets and outlets
Remove excess sediment
Trim back bunch grasses
Deadhead spent wildflowers and disperse seeds
Trim back frost damaged foliage
Pull invasive weeds
Leave native annuals
Light or structural pruning if necessary
Remove trash
WINTER dec 1 - feb 15 Pull invasive weeds
Leave native annuals
Deadhead spent wildflowers and disperse seeds
Trim back frost damaged foliage
Turn irrigation off (generally November-March)
Remove trash
GSI Contacts :
City of Tucson Storm to Shade Program www.climateaction.tucsonaz.gov/pages/gsi www.tucsonaz.gov/gsi
Other GSI Partners:
Tucson Clean & Beautiful: GSI Mini-Grants Program tucsoncleanandbeautiful.org/trees-for-tucson/gsi-mini-grants/
Pima County Flood Control District webcms.pima.gov/government/flood_control/
File details come from the government source that posted it. Updated .