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Pervious Surface Requirements In zones R‐1 through R‐4 Applies when increasing existing lot occupancyby 10% or 25% for historic structures Pervious grass; mulched groundcover; plants;trees; permeable pavers; and decks or porches

Landscaping for Surface Parking Minimum 10% of lot landscaped Landscape end islands of 9 spaces Trees must be min. 2.5” dbh atplanting Plant 4’ from protective barriers Special exceptions if impracticable

LANDSCAPE ELEMENTS

Landscape Element FormatLandscape ElementIntegrationRequirementsCoordinate betweenLandscape ElementsCalculating lan gn &ConstructionGuidelines

Soils and AmendmentsDepth 24” 0.3Depth 24” 0.6 Depth is measured by total uncompacted soiland subsoil. Existing soils with vegetation are creditedwith 24” depthDesign Existing soils – specify protection fencing orstockpiling Disturbed topsoil – incorporate compost Imported topsoil – meet specificationsConstruction Area and depth of uncompacted soil Subgrade preparation and drainage Soil testing – imported and disturbed soils Soil stabilized with vegetative cover or mulchCredit: Univ. Cornell UniversityCredit: Univ. Mich. Biological Station

BioretentionMultiplier0.4DesignConstruction Extents of bioretention and pre‐treatment area Rain garden, bioretention, stormwater planters, dry swalesSpecify primarily native plantingsSoils to comply with Stormwater Management Guidebook.Considerations – trees near underdrains Surface area Soil media Plant quality and installation.

New & Existing PlantingsVariable0.2‐0.6 Caliper measurements for tree size Transplanted trees are credited as new Multi‐stem trees – measure ½ of 3largest trunksGreen Area Ratio Landscape ElementsEquivalent Square Footage(ft2 per plant/tree)Groundcovers, or other plants less than 2 feet tall at maturityPlants, not including grasses, at least 2 feet tall at maturitySquare footage at maturity9Tree canopy for trees 2.5–6 inches in diameter50Tree canopy for trees 6–12 inches in diameter250Tree canopy for trees 12–18 inches in diameter600Tree canopy for trees 18–24 inches in diameter1,300Tree canopy for trees larger than 24 inches in diameter2,000

New & Existing ies ANLA Standards (rootball, caliper, branching, height) Specify perennials and woody plants (not annuals)unless for food cultivation Plant spacing and rooting depth Scheduling ‐ planting season and constructionsequence Plant material inspection before/during installation Layout as per plan Planting hole preparation

Tree Protection2.5‐6”dia. 0.56‐24” dia. 0.7 24” dia. 0.8 Variable multipliers DBH MeasurementCredit: U. of MinnesotaDesign Tree Survey – consider additional coordination with ISAArborist for tree condition assessment Tree preservation plan – identify CRZ (or dripline) protection,including fencing and other protection or design measuresConstruction Preconstruction meeting – protection measures installed During construction ‐ adherence to protection plan Adjust GAR plan as necessary if tree protection not adheredto during construction.

Vegetated WallsMultiplier0.6 Measure along ground plane. Standard vegetated width is 1 foot. Linear coverage is expected growth in soilarea along vertical elementDesign 5’ from side or rear lot lineMay require harvested stormwater irrigationPlant cultural requirements12‐foot minimum heightConstruction Area and spacing of plantingsVerify installation of vertical supportInstallation and function of irrigationPlant quality and establishmentSource: Tournesol Siteworks

Vegetated RoofsExtensive 0.6Intensive 0.8DesignConstruction Extensive (2‐8” soil) – groundcover vegetation built into score Intensive ( 8” soil) – additional credit for plants 2’ ht. Supplemental irrigation required (hose bib, drip, spray) Harvested stormwater irrigation connection if proposed Vegetation coverage and quality Depth of soil media Suitable drainage for plantings

Enhanced Tree GrowthSystemsCredit: Cornell UniversityMultiplier0.4DesignConstruction Cannot exceed 1/3 of total GAR score along withpermeable paving Permeable pavers may be placed over Enhanced TreeGrowth systems Minimum 24” soil depthUnderneath pavement and adjacent to tree pitsNeither contaminated or compacted (CERCLA)Consider passive irrigation (pavers, drain inlets with pipe) Area and depth of soil media Irrigation and drainage (as necessary) Topsoil meets approved specification

Permeable Paving6‐24” soil/gravel 0.4 24” soil/gravel 0.5DesignConstruction Cannot exceed 1/3rd of GAR total score in combinationwith “enhanced tree growth” Shall meet the guidelines in Stormwater ManagementGuidebook Vegetated pavers ‐ use for overflow parking only Area Depth of aggregate or soil structural layer

Renewable EnergyMultiplier0.5 Square footage of arrayDesign Solar photovoltaic and solar thermal Site plan with array location and dimensions Schematic plan for electrical or plumbing systemsConstruction Visually confirm area after certification/inspectorsignoff

Water FeaturesMultiplier0.2DesignConstruction Area of water element Pools, fountains, constructed wateramenities Harvested rainwater ‐ 50% annual flowWater feature underwater 6 mo./ yr. (min.)Submit plumbing documents, water budgetWater must recirculate Confirm area per approved plan Confirm connection to harvestedrainwater

Harvested Stormwater Irrigation [Bonus]Multiplier 0.1 Bonus ‐ green roof, green wall, new plantings Irrigation from Contributing drainage area and cisternDesign Submit schematic irrigation/drainage plan Irrigation area Delivery system (drip vs spray) Anticipated water demand (inch/week, % harvested) DrainageConstruction Area of irrigation System is functional and connected to cistern/rain barrel

Native Plants [Bonus]Bonus Feature0.1DesignConstruction New plants and tree preservation Green roof Vegetated wall USFWS ‐ Native Plants for WildlifeConservation Landscaping: Referenced as native Non‐invasiveSource: Northcreek Nurseries Plant speciesSource: Northscaping, Inc.

Food Cultivation [Bonus]Bonus Feature0.1DesignConstruction Soil area Green roof Vegetated wall Plantings Accessible to building occupants Water source is available Annuals, perennials, woody species Planting of crops Soil is stabilized

LANDSCAPE AREAS ALL PLANTINGSProvide supplemental watering if rainfall is less than 1 inch perweek during the first two growing seasons.Conduct weeding as necessary to reduce competition betweenweeds and new plantings for nutrients, soil moisture, and sunlight.Replace mulch as necessary to reduce competition for availablemoisture and nutrients.Monitor the plantings for disease or stress and modify culturalpractice as necessary. Employ an integrated pest management(IPM) approach if possible.Remove dead plant material and replant in the next appropriateMaterial sourceCompost should be well‐decomposed material, stable, free of weeds, contaminants and growing season.foul odors. Compost may be derived from yard waste (decomposed leaves, grass clippings,TREES AND SHRUBSFor trees, install slow leak watering bags or tree buckets during thebranches) or food waste.first two growing seasons and water as necessary to supplementMulch can be derived from organic sources such as shredded bark, or leaf mulch.precipitation if less than 1 inch per week.Inspect trees for signs of dead, diseased, or crossing branches andBIORETENTIONprune accordingly. Remove hazard limbs especially fromFrequencyMaintenance Tasksestablished trees. Never remove more than 20% of the tree canopyUpon establishmentFor the first 6 months following construction, the practice and CDA should be inspected at during pruning activities in any year.least twice after storm events that exceed 1/2 inch of rainfall. Conduct any needed repairs Spread mulch to 2‐4 inch depth.Maintain the health of the tree by limiting all grade changes andor stabilization.other soil disturbance underneath the tree’s Critical Root Zone.Inspectors should look for bare or eroding areas in the contributing drainage area oraround the bioretention area, and make sure they are immediately stabilized with grass PERENNIALS AND GROUNDCOVERSIn the early spring, deadhead top‐growth from perennials andcover.warm‐season grasses.One‐time, spot fertilization may be needed for initial plantings.Watering is needed once a week during the first 2 months, and then as needed during firstPeriodically divide perennials as necessary to encouragerejuvenated growth.growing season (April‐October), depending on rainfall.Remove and replace dead plants. Up to 10% of the plant stock may die off in the first year, Spread mulch at a maximum 2‐inch depth.so construction contracts should include a care and replacement warranty to ensure that TURFGRASSTest soil for pH and apply lime only as necessary.vegetation is properly establishedMaintain turfgrass at an increased height to reduce weedgermination. Never mow more than one third of the grass height.At least 4 times per yearLeaving grass clippings in‐place after mowing requires less fertilizerMow grass filter strips and bioretention with turf coverCheck curb cuts and inlets for accumulated grit, leaves, and debris that may block inflow application.Regularly monitor and over‐seed bare spots to prevent weedestablishment.Twice during growing seasonIn late fall, core aerate and topdress with organic matter.Spot weed and mulchSOILS AND AMENDMENTSSeasonal applicationMulch – Apply yearly or as necessary to replace decomposed mulch.Compost – Apply compost yearly at 1–2 inch depth. Coarse textured sand and clay soilsrequire greater compost addition than loamy soils. The organic matter content of thechosen compost will determine the depth appliedFertilizer – If choosing to apply fertilizer, perform a soil test for nutrient levels only afterincorporating compost into topsoil. This will avoid over‐application of nutrients, ascompost itself will increase the nutrient content.When using harvested stormwater irrigation, valvesand fertilizer injectors should be checked for function,and the irrigation pipes checked for leaks. Schedulefrequent irrigation inspections. Drip irrigation emittersshould be checked during operation to ensure wateris being delivered to all panels. Winterize irrigationsystems as per the irrigation specification.Schedule regular plant maintenance duringestablishment and ongoing growth. Inspect thevegetated wall for signs of disease, inadequateirrigation, and erosion.HARVESTED STORMWATER IRRIGATIONCisternThe cistern must be cleaned yearly. To clean, use asubmersible pump to remove the water. Brush wallswith a hard bristle brush or use a high pressurecleaner.Purpose of the maintenance is to remove thesediment that inevitably deposits on the cistern's floorand which may give rise to parasitic fermentation andodor. The rate at which the sediment accumulatesdepends on the region's atmospheric pollution (fordust), the roof type, and the quality of the set‐upupstream from the cistern's storage compartment.A fine mesh filter placed between the roof gutter'smain downspout and the sedimentation basin willsubstantially delay the accumulation of sediment inthe barrel or cistern. Additionally, a sedimentationbasin equipped with an appropriate trapped overflowthat prevents the passage of floating impurities canwork. Filters need to be cleaned monthly.Cisterns and rain barrels should be dewatered oftento ensure available volume on the onset of rainevents.LANDSCAPE MAINTENANCE PLANAnnuallyConduct a maintenance inspectionSupplement mulch in devoid areas to 3” depthPrune trees and shrubsRemove sediment in pre‐treatment cells and inflow pointsOnce every 2–3 yearsRemove sediment in pretreatment cells and inflowointsVEGETATED WALLSLiving FacadesPeriodically inspect roof gutters and drains for clogging withvegetation or debris.Cable systems may require re‐tensioning or inspection of theintegrity of wall tie‐ins.Schedule regular plant maintenance during establishment andongoing growth. Inspect the plants for signs of disease, weedcompetition, training along the support structure, and pruningneeds.As needed Add reinforcement planting to maintain desired vegetation density Remove invasive plants using recommended control measures Remove any dead or diseased plantsLiving WallsIndividual vegetated panels from living walls should be removed toinspect the wall and support structures for drainage and anchorageissues. Clean all drains and gutters yearly.IrrigationConduct frequent inspections to verify integrity ofirrigation system.Periodically review the pressure regulators, filters,controller, sensors, valves, sprinkler heads and othersystem components to verify they meet originaldesign criteria for efficient operation and uniformwater distribution.Ensure that replacement hardware used for systemrepairs matches the existing hardware, and is inaccordance with the design. Ensure that systemmodifications are in keeping with designspecifications and do not cause water demand toexceed the system’s hydraulic capacity.Winterize irrigation systems and re‐establishoperation in the spring.

Questions & Answers For additional information:ddoe.dc.gov/GAR Markku McGlynn David Wooden Rebecca Stack Laine Cidlowski

Seattle Green Factor Livability Ecosystem Services Climate Change Adaptation. Stated Priorities: "Emphasizing landscape in site planning. Earlier involvement in the design process allows landscape architects to exercise more creativity and develop innovative design solutions."