Soils, Plantings, And Irrigation For Bioretention Faciltiies

1y ago
9 Views
0 Downloads
377.04 KB
20 Pages
Last View : 2m ago
Last Download : n/a
Upload by : Julia Hutchens
Transcription

BAppendixSoils, Plantings, and Irrigationfor Bioretention FacilitiesAdditional guidance for design and construction ofbioretention facilities and flow-through plantersBioretention facility owners are responsible for ensuring the followingstandards of performance are achieved throughout the life of the facility: Runoff must percolate through the imported bioretention soil mix at aminimum rate of 5" per hour. Plantings must be maintained in a healthy condition without use ofconventional fertilizers or pesticides. Irrigation systems must minimize water use and be controlled toprevent overwatering and underdrain flow during dry weather.As described in Chapter 5, municipalities will periodically verify these standardscontinue to be achieved. Operation and maintenance verification is required by themunicipalities’ stormwater NPDES permit issued by the Regional Water QualityControl Board.The design criteria and checklistsand other guidance in Chapter 4—including the design sheets on pp.63-78—aimtoensurenewbioretention facilities and planterboxes can reliably meet thesestandards of performance.The additional guidance in thisAppendix will assist applicants andAppendix B ContentsSoils . B-2Plantings . B-7Irrigation . B-8Attachment B-1:Plant Recommendations for Bioretention Facilities andPlanter BoxesJanuary 2009

S T O R M W A T E RC . 3C O M P L I A N C Etheir designers as they proceed from initial planning through design andconstruction.Responsibility for design, construction, maintenance, and performance ofstormwater treatment and flow-control facilities and their components restswith the applicant or property owner.SoilsSoils for bioretention areas must meet two objectives: Be sufficiently permeable to infiltrate runoff at a minimum rate of 5"per hour during the life of the facility, and Have sufficient moisture retention to support healthy vegetation.I C O N K E YHelpful TipSubmittal Requirement Terms to Look Up References & Resourcescompost).Some native loamy sands may be suitable for bothobjectives; however, such soils are rare in Contra Costaand are not generally available from suppliers.Achieving both objectives with an engineered soil mixrequires careful specification of soil gradations and asubstantial component of organic material (typicallyThe Contra Costa Clean Water Program has developed specifications for twobioretention soil mixes. Local soil products suppliers have expressed interest indeveloping “brand-name” mixes that meet theseCreditspecifications. At their sole discretion, municipal This Appendix was preparedconstruction inspectors may choose to accept test results and based on recommendationsEnvironmentalcertification for a “brand-name” mix from a soil supplier. A by WRAConsultants, Inc.www.wra-ca.comlist of suppliers who have submitted test results andcertification to the Program is on the Program website.Updated soil and compost test results may be required; tests must be within 120days prior to the delivery date of the bioretention soil to the project site.Typically, batch-specific test results and certification will be required for projectsinstalling more that 100 cubic yards of bioretention soil. SOIL SPECIFICATIONBioretention soils should meet the following criteria.1.General RequirementsBioretention soil shall achieve a long-term, in-place infiltration rate of atleast 5 inches per hour. Bioretention soil shall also support vigorous plantgrowth.January 2009B-2

A P P E N D I XB — S O I L S ,P L A N T I N G S ,A N DI R R I G A T I O NBioretention Soil shall be a mixture of topsoil or fine sand, and compost,measured on a volume basis.Mix A – Topsoil Blend10%-20% Topsoil50%-60% Fine Sand30%-40% CompostMix B – Fine Sand Blend60%-70% Fine Sand30%-40% Compost1.1.SubmittalsThe applicant must submit to the municipality for approval:A.A sample of mixed bioretention soil.B.Certification from the soil supplier or an accredited laboratorythat the Bioretention Soil meets the requirements of thisguideline specification.C.Grain size analysis results of the fine sand componentperformed in accordance with ASTM D 422, Standard TestMethod for Particle Size Analysis of Soils.D.Quality analysis results for compost performed in accordancewith Seal of Testing Assurance (STA) standards, as specified inSection 1.4.E.Organic content test results of mixed Bioretention Soil.Organic content test shall be performed in accordance with byTesting Methods for the Examination of Compost andComposting (TMECC) 05.07A, “Loss-On-Ignition OrganicMatter Method”.F.A description of the equipment and methods used to mix thesand and compost to produce Bioretention Soil.G.Provide the following information about the testinglaboratory(ies) name of laboratory(ies) including1)contact person(s)2)address(es)3)phone contact(s)4)e-mail address(es)B-3January 2009

S T O R M W A T E RC . 35)1.2.C O M P L I A N C Equalifications of laboratory(ies), and personnel includingdate of current certification by STA, ASTM, or approvedequalSand for Bioretention SoilA.GeneralSand shall be free of wood, waste, coating such as clay, stonedust, carbonate, etc., or any other deleterious material. Allaggregate passing the No. 200 sieve size shall be non-plastic.B.Sand for Bioretention Soil TextureSand for Bioretention Soils shall be analyzed by an accreditedlab using #200, #100, #40, #30, #16. #8, #4, and 3/8 inchsieves (ASTM D 422 or as approved by municipality), and meetthe following gradation:Sieve SizePercent Passing (by weight)MinMax3/8 inch100100No. 490100No. 870100No. 164095No. 301570No. 40555No. 100015No. 20005Note all sands complying with ASTM C33 for fine aggregatecomply with the above gradation requirements.1.3.Topsoil for Bioretention SoilA.GeneralTopsoil shall be free of wood, waste, or any other deleteriousmaterial.B.Topsoil for Bioretention Soil TextureThe overall topsoil texture shall be loamy sand as analyzed byan accredited laboratory. The overall dry weight percentagesshall be 60-90% sand, with less than 20% passing than the #200sieve and less than 5% clay of the total weight with no gravel.January 2009B-4

A P P E N D I X1.4.B — S O I L S ,P L A N T I N G S ,A N DI R R I G A T I O NComposted MaterialCompost shall be a well decomposed, stable, weed free organic mattersource meeting the standards developed by the US CompostingCouncil (USCC). The product shall be certified through the USCCSeal of Testing Assurance (STA) Program (a compost testing andinformation disclosure program).A.Compost Quality AnalysisBefore delivery of the soil, the supplier shall submit a copy oflab analysis performed by a laboratory that is enrolled in the USComposting Council’s Compost Analysis Proficiency (CAP)program and using approved Test Methods for the Evaluationof Composting and Compost (TMECC). The lab report shallverify:1)Feedstock Materials shall be specified and include one ormore of the following: landscape/yard trimmings, grassclippings, food scraps, and agricultural crop residues.2)Organic Matter Content: 35% - 75% by dry wt.3)Carbon and Nitrogen Ratio: C:N 25:1.4)Maturity/Stability: shall have a dark brown color and asoil-like odor. Compost exhibiting a sour or putrid smell,containing recognizable grass or leaves, or is hot (120F)upon delivery or rewetting is not acceptable. In additionany one of the following is required to indicate stability:5)a.Oxygen Test 1.3 O2 /unit TS /hrb.Specific oxy. Test 1.5 O2 / unit BVS /c.Respiration test 8 C / unit VS / dayd.Dewar test 20 Temp. rise ( C)e.e. Solvita 5 Index valueToxicity: any one of the following measures is sufficientto indicate non-toxicity.a.NH4- : NO3-N 3b.Ammonium 500 ppm, dry basisc.Seed Germination 80 % of controld.Plant Trials 80% of controlB-5January 2009

S T O R M W A T E RC . 3C O M P L I A N C Ee.6) e. Solvita 5 Index valueNutrient Content: provide analysis detailing nutrientcontent including N-P-K, Ca, Na, Mg, S, and B.a.Total Nitrogen content 0.9% or above preferred.b.Boron: Total shall be 80 ppm; Soluble shall be 2.5 ppm7)Salinity: Must be reported; 6.0 mmhos/cm8)pH shall be between 6.5 and 8. May vary with plantspecies.B.Particle size: 95% passing a 1/2” screen.C.Bulk density: shall be between 500 and 1100 dry lbs/cubic yardD.Moisture Content shall be between 30% - 55% of dry solids.E.Inerts: compost shall be relatively free of inert ingredients,including glass, plastic and paper, 1 % by weight or volume.F.Weed seed/pathogen destruction: provide proof of process tofurther reduce pathogens (PFRP). For example, turnedwindrows must reach min. 55C for 15 days with at least 5turnings during that period.G.Select Pathogens: Salmonella 3 MPN/4grams of TS, orColiform Bacteria 10000 MPN/gram.H.Trace Contaminants Metals (Lead, Mercury, Etc.) Product mustmeet US EPA, 40 CFR 503 regulations.I.Compost TestingThe compost supplier will test all compost products within 120calendar days prior to application. Samples will be taken usingthe STA sample collection protocol. (The sample collectionprotocol can be obtained from the U.S. Composting Council,4250 Veterans Memorial Highway, Suite 275, Holbrook, NY11741 Phone: 631-737-4931, www.compostingcouncil.org). Thesample shall be sent to an independent STA Program approvedlab. The compost supplier will pay for the test.PLACEMENT AND COMPACTION OF BIORETENTION SOILSPlace the bioretention soil in 8" to 12" lifts. Lifts are not to be compacted but areplaced to reduce the possibility of excessive settlement. Allow time for naturalJanuary 2009B-6

A P P E N D I XB — S O I L S ,P L A N T I N G S ,A N DI R R I G A T I O Ncompaction and settlement prior to planting. Bioretention soil may be watered toencourage compaction.Plantings PLANT SELECTION GUIDELINESThe plants tabulated in Attachment B-1 were selected for the followingcharacteristics: Adaptation to Contra Costa’s climate Drought tolerance Adaptation to well-drained soils Adaptation to low soil fertility Allow infiltration Are not invasive weeds Do not have aggressive rootsCharacteristics noted in the table, including irrigation preferences and ability totolerate heat, coastal conditions, flooding, and wind should be considered whenselecting plants.This list is not comprehensive, nor will all these species succeed at every site.Selection for a particular site should be done by experienced professionals familiarwith the plants and site conditions. Avoid planting species on the CaliforniaInvasive Plant Council’s invasive plant inventory list. PLANT INSTALLATIONTrees and large shrubs installed in bioretention facilities are susceptible to blowingover before roots are established. They should be staked securely. Three stakes pertree are recommended at windy sites. Straps should be inspected once or twice ayear and removed once trees are established to prevent girdling. FERTILIZATIONDue to the potential for conveying nutrients to storm drains, no fertilizer shouldbe added to bioretention facilities or planter boxes. Compost tea, available fromvarious nurseries and garden supply retailers, may be applied at a recommendedrate of 5 gallons mixed with 15 gallons of water per acre.Compost tea can be applied up to two weeks prior to planting and once per yearbetween March and June. Application is not recommended when temperatures areB-7January 2009

S T O R M W A T E RC . 3C O M P L I A N C Ebelow 50 F or above 90 F or when rain is forecast in the next 48 hours.Additional applications may be made as needed to correct nutrient deficiencies. MULCHMulch is not required but is recommended for the purpose of retaining moisture,preventing erosion and minimizing weed growth. Aged mulch, also called compostmulch, reduces the ability of weeds to establish, keeps soil moist, and replenishessoil nutrients. Aged mulch can be obtained through soil suppliers or directly fromcommercial recycling yards. Apply 1" to 2" of composted mulch, once a year,preferably in June following weeding.Compared to bark mulch, aged mulch has somewhat less of a tendency to floatinto overflow inlets during intense storms. To reduce mulch entering overflowinlets, it is recommended to use atrium or beehive grates with ¼" openings overoverflow inlets. WEED CONTROLWeeds should be controlled primarily by manual methods and soil amendment. Inresponse to problem areas or threatening invasions, corn gluten, white vinegar,vinegar-based products such as Burn-out, or non-selective natural herbicides suchas Safer’s Sharpshooter may be used. PEST AND DISEASE CONTROLSynthetic pesticides should not be used on bioretention facilities. Beneficialnematodes and non-toxic controls may be used. Acceptable natural pesticidesinclude Safer Aphid, Whitefly, and Mealybug Killer, Safer Tree and ShrubInsect Attach, Safer for Evergreens, and Neem oil.IrrigationBioretention soils have a high infiltration rate and require a different irrigationsystem design than what is typically used for heavy clay soils in Contra CostaCounty. Irrigation systems must be designed to minimize water use, avoidoverwatering, and prevent the underdrain discharges during dry weather.Bioretention facilities and planter boxes may need to be irrigated more than once aday. Irrigation controls should allow separate control of times and durations ofirrigation for bioretention facilities and planter boxes vs. other landscape areas.are strongly encouraged. Available controllers mayaccess weather stations, use sensors to measure soil temperature and moisture, andallow input of soil types, plant types, root depth, light conditions, slope, andusable rainfall.Smart irrigation controllersare strongly recommended over spray irrigation. Use multiple,lower-flow (one-half to two gallons per hour) emitters in fast-drainingDrip emittersJanuary 2009B-8

A P P E N D I XB — S O I L S ,P L A N T I N G S ,A N DI R R I G A T I O Nbioretention soils. Use two or more emitters for perennials, ground covers, andbunchgrasses. Four to six emitters may be needed for larger shrubs and trees.Some types of emitters encourage horizontal distribution of water.Spray heads must be positioned to avoid direct spray into bioretention facility orplanter box outlet structures. References and Resources Recommendations for Soils Specification, Planting, and Irrigation of Bioretention Facilities,WRA Environmental Consultants, November 5, 2008. US Composting Council ASTM International Plant List and Planting Guidance for Landscape-Based Stormwater Measures. Appendix B in the Alameda CountyClean Water Program C.3 Technical Guidance (2006). Plants and Landscapes for Summer Dry Climates. Nora Harlow, Ed. East Bay Municipal Utility District, Oakland California Native Plants for Your Garden and Wildlife, Las Pilitas Nursery, 2008. Native Treasures: Gardening with the Plants of California. M. Nevin Smith, 2006. University of California Press. The Califlora Database, 2008. California Invasive Plant Council A Guide to Estimating Irrigation Water Needs of Landscape Plantings in California, University of CaliforniaCooperative Extension and California Department of Water Resources Our Water Our World, website to developed to assist consumers in managing home and garden pests in away that helps protect water. Bay-Friendly Landscaping for Professionals, a whole systems approach to the design, construction, andmaintenance of the landscape to support the integrity of the San Francisco Bay watershed. University of California Statewide Integrated Pest Management (IPM) ProgramB-9January 2009

Plant Recommendations for Bioretention Facilities and Planter BoxesGrasses and Grass-like PlantsScientific nameCommon nameBromus carinatusCalifornia bromeBouteloua gracilisblue gramaCarex densadense sedgeCarex obnuptaslough sedgeCarex praegracilisclustered field sedgeCarex subfuscarusty sedgeCarex divulsaBerkeley sedgeDeschampsiacespitosatufted hairgrassDistichlis spicatasalt grassEleocharis palustriscreeping spikerushElymus glaucusblue wildryeFestuca californicaCalifornia fescueFestuca idahoensisIdaho fescueFestuca rubrared fescueFestuca rubra 'molate'molate fescueHordeumbrachyantherumAttachment B-1Light PreferenceSunPartShade Size (feet)WateringHt.WidthLM21 1.51 11211.51.51111210.33111.5222 11 11.5 11.5 1.51HSummerok Wind CANative Tolerates no summer water, good for nonirrigated remote sites ok okok Other Notes Great for swalesAKA Carex tumulicola,. Full sun alongcoast.Can look weedyLooks like bermuda grass, withstands foottraffic, for soils with high salt ok ok ok ok Can mow. Needs light summer water at hotsitesok Can mow. Lawn alternativeok cCan mow. Lawn alternativeok Flood Coast Heat Tolerates 1 of 11 good for grazing, difficult to mow, messylooking lawnJanuary 2009

Plant Recommendations for Bioretention Facilities and Planter Boxesmeadow barleyJuncus patensblue rushLeymus triticoidescreeping wildryeMelica californicaCalifornia melicaMelica imperfectmelicMuhlenbergia rigensdeergrassNasella pulchrapurple needlegrassNassella lepidafoothill needlegrassPhalaris californicaCalifornia canarygrassAttachment B-1 131 11 11 3321 1.51 1.51 2 ok okok ok ok 2 of 11 ok Can mow. Recommended for swales. Part shade inland, light water in Summer tokeep green or goes dormant Can be aggressive spreaderJanuary 2009

Plant Recommendations for Bioretention Facilities and Planter BoxesHerbaceous Perennials and GroundcoversScientific nameCommon nameAchillea filipendulinafernleaf yarrowAchillea millefoliumcommon yarrowAchillea tomentosawoolly yarrowAloe striatacoral aloeArctostaphyloshookeriMonterey manzanitaArctostaphylos arf plumbagoEpilobium canumCalifornia fuchsiaEriogonumfasciculatumflattop buckwheatEschscholziacalifornicaCalifornia poppyFragaria chiloensisbeach strawberriesGazania spp.treasure flowerIris douglasianaDouglas irisLight PreferenceSunPart Attachment B-1Shade Size (feet)WateringHt.WidthLM33 1.51 11.522 14 115 0.755 14 34 11 0.32 0.52 1.52 HSummer Tolerates ok ok okok okCoastFloodWind ok Heat ok ok 3 of 11Better in part shade in hot sitesFull sun at coast, part shade inland.Cultivars to try include 'emerald carpet,''Point Reyes,' 'San Bruno Mountain'depending on site Good for hot sitesSun along coast, afternoonshade inland Other Notes ok CANative Also, Iris hybrids January 2009

Plant Recommendations for Bioretention Facilities and Planter BoxesScientific nameCommon nameLotus scopariusdeerweedLupinus bicolorminiature lupineMimulus aurantiacuscommonmonkeyflowerMimulus cardinalisscarlet monkeyflowerPolygonum capitatumpink knotweedPrunella vulgarisself healRudebeckia californicaCalifornia coneflowerSalvia clevelandiiCleveland sageScaevola 'mauveclusters'fan flowerSedum spathulifoliumstone cropSisyrinchium bellumblue eyed grassSisyrinchiumcalifornicumyellow eyed grassSolidago californicaCalifornia goldenrodStachys byzantinelamb's earsVerbena tenuisectamoss verbenaAttachment B-1Light PreferenceSunPartShade 43 11 33 330.542 L 14MH Tolerates Summer ok Flood okok 111132 13 0.55 Other Notes Adds nitrogenAggressive

Soils, Plantings, and Irrigation for Bioretention Facilities . Additional guidance for design and construction of bioretention facilities and flow-through planters . ioretention facility owners are responsible for ensuring the following standards of performance are achieved throughout the life of the facility:File Size: 377KB