WIXLIB

SiteDevelopmentCONSTRUCTION ENTRANCE / EXITA pad of coarse aggregate at the construction entrance/exitwill reduce the tracking of soil from construction traffic ontoa public street. Sediments from the tire treads are knockedloose by the angular stones and are trapped in the voidsbetween the stones.COMPANION BMPs: Sediment Trapping andSediment BarriersCONSTRUCTION SPECIFICATIONS The entrance/exit pad should have a length of50 feet or more and a 12-foot minimum width(or as appropriate to contain the wheel base ofconstruction vehicles plus 3 feet on either side). The pad should be 6 inches or more thick withangular aggregate (2-3 inch diameter). Appropriatereclaimed concrete material may be used. The aggregate should be placed over a geotextilefilter to prevent the stones from pushing into thenative soil. At the bottom of slopes, a diversion ridge should beprovided to intercept runoff. Berms may be necessary to divert water aroundany exposed soil, and runoff should be directed to asediment trap. The wheels of construction equipment may bewashed prior to exiting the site. Washing should beperformed in an area that drains to a sediment trapor basin.2

3SiteDevelopmentThe pad should be inspectedweekly as well as before andafter a storm. The pad mayhave to be replaced if the voidsbecome filled with sediment.Street sweeping may benecessary.

SiteDevelopmentDUST CONTROLDusty conditions occur when a disturbed site or road surfacehas dried out; and dust from wind erosion becomes anenvironmental or public concern. Note that a gravel surfacewithout fines results in wash-boarding.Stabilize all laydown areasand all unpaved surfaces witha base gravel or coarse gravelas soon as possible. Usetraffic control to restrict speedand route.Water Application withfrequent reapplication duringwarm sunny days will mitigatedust. The distribution of watershould not cause turbid runoff.Sweep and Vacuum pavedroad surface when dry. Sweepfrom the center line to theedge of the travel way. Do notsweep into a waterbody orwetland. The public roadwaymay also require sweeping.Calcium Chlorideapplications are more cost-effective on larger sites (30%calcium chloride is recommended for most gravel surfaces orfollow the supplier’s guidance).Soil Binders may require pre-wetting, a 24-hour curingtime and minimum temperatures for use. Asphalt or oil-basedbinders are not allowed.4

The winter construction period runs from October 15 throughMay 1st. Additional stabilization measures should beprovided by November 1st for winter and spring snowmeltif a construction site is not permanently stabilized withpavement, a gravel road base, 95% mature vegetation cover,erosion control mulch, or riprap.Ideally, permanent seeding should occur 45 days before thefirst killing frost (different dates for different Maine locations);otherwise, overwinter mulching is necessary. See theVegetation section for more information.COMPANION BMPs: Mulching, SedimentTrapping, Vegetation and SlopesOverwinter Construction DifficultiesCannot be established outsideVegetative Ground Coverof growing season.Snow or icing may clogRunoff Diversiondiversion structures.Should be installed beforeSedimentation Basinsthe ground is frozen. Can beoverwhelmed by spring flows.Difficult to install on frozenSilt Fenceground. Often fails duringspring melt.Cannot be anchored on frozenErosion Control Blanketsground.Stabilizers are ineffective inHydroseedingcold temperatures.Cannot be established outsideVegetated Swalesof growing season.Base gravel on driving/parkingImpervious Stabilizationareas. Pavement cannot beinstalled in winter.5SiteDevelopmentOVERWINTER CONSTRUCTION

SiteDevelopmentOverwinter Hay Mulch should be applied at double thenormal rate (150 pounds per 1000 square feet or 3 tons/acre) and should be anchored with netting (peg and twine)or a tackifier to prevent mulch displacement before freezingconditions. No soil should be visible through the mulch. Haymulch cannot be applied over snow.Dormant Seeding and Mulch should be applied at3 times the specified amount after the first killing frost. Alldormant seeding beds should be covered with overwinterhay mulch or an anchored erosion control blanket.Temporary vegetation should be applied by October1st with winter rye at 3 pounds per 1000 square feet, andmulched with anchored hay at 75 pounds per 1000 squarefeet or with erosion control blankets. If the rye fails to grow atleast three inches and have 75% coverage by November 1st,the area should be stabilized for overwinter protection.Erosion control mix is the best overwinter cover, but isnot recommended for slopes steeper than 1:1 or in areaswith flowing water.Erosion Control Blankets should be used on slopeswhere hay would be disturbed by wind or water. The mattingshould be installed, anchored and stapled in accordance withthe manufacturer’s recommendations. Full contact betweenthe blanket and the soil is critical for an effective erosioncontrol cover.Riprap should be properly sized and installed to ensurelong-term stability. In the winter, newly constructed ditchesand channels should be stabilized with riprap. Widening ofthe channel may be required to accommodate the placementof stones. Angular riprap is preferred to round stone(tailings).6

If construction occurs afterNovember 1st, all disturbedareas should be stabilized daily.Stabilization during the winterconstruction period may includemulching, erosion control mix,erosion control blankets, andstone.Daily inspections in the winterare important if the constructionis active. Any erosion ordischarges should be repairedimmediately.7SiteDevelopmentSod may be used for late-season stabilization (after October1st), but it is not recommended for slopes steeper than 3:1or in areas with groundwater seeps. Follow the supplier’sinstructions.

SiteDevelopmentWATER DIVERSIONA water diversion consists of a channel constructed acrossor above a work site to direct runoff away from a disturbedarea to stable discharge point that is unlikely to erode. It caneither be an excavated ditch that intercepts groundwaterand surface water, or a berm that diverts surface runoff.A permit may be required for dewatering a wetland orwaterbody in accordance with Maine Natural ResourceProtection Act (NRPA). For additional information pleasecontact your nearest DEP regional office.COMPANION BMPs: Riprap, Mulching, SedimentTrapping and VegetationA temporary diversion structureis most important during astorm event until the area isrevegetated and stable.The water diversion shouldalways be kept clear ofsediment and debris.Upon final stabilization, atemporary diversion should berestored to the intended grade.8

The condition of the site topography, land use,soil type and length of slope should determine thelocation of a diversion. The diversion should be angled away from theslope (with a 2-3% downward gradient) for positivedrainage to a stable discharge point (plunge pool,level spreader or energy dissipater). Diversions designed to protect buildings and roadsshould have the capacity to manage the runoff froma large storm event. Diversions should not be used below high sedimentproducing areas unless maintained and monitoreddaily. Exposed soils should be shaped, graded, andstabilized immediately unless a diversion willbe provided to direct any runoff to a temporarysedimentation structure. All diversion dikes and berms should be compactedand stabilized with material that is appropriate forthe slope and expected runoff (erosion controlblankets, gravel or riprap). A diversion berm should be wide and the dike deepenough to allow for maintenance access as well ascontain the volume of runoff. Any gullies or depressions crossed by the diversionshould be filled, compacted, and stabilized. On long slopes, multiple diversions will managesmaller volumes of runoff and be less likely to fail.9SiteDevelopmentCONSTRUCTION SPECIFICATIONS

SiteDevelopmentA permanentvegetated diversionneeds to be stabilizedearly during thegrowing season (priorto September 1st) forfull vegetative coverbefore winter.10

Dewatering occurs in 3 phases: removing the water fromthe excavation area (gravity drain, mechanical pumping,siphoning or using the bucket of construction equipment);providing settlement from the collected water (sedimentbasin or trap, bag, etc.); and providing a stable dischargepoint.COMPANION BMPs: Sediment Trapping,Vegetation, and SlopesThe water removedfrom the excavationarea should either bedischarged as sheet flowto a buffer area or to atreatment structure.During dewatering,frequently inspect thereceiving area for signsof erosion, concentratedflows or sedimentdischarge and repairimmediately.11SiteDevelopmentEXCAVATION DEWATERING

SiteDevelopmentCONSTRUCTION SPECIFICATIONS The discharge to the sediment treatment areashould never exceed its capacity. Divert upgradient clean runoff away from anexcavated area. Avoid discharging to an unstable area, newlyvegetated or within 100 feet of a natural resource. A positive displacement pump is recommendedwhen pumping is necessary and the water containsa lot of sediment. The elevation of the pump above the water intakeand the distance of the discharge hose will greatlyaffect its pumping capacity. Any channel dug for discharging water should bestabilized with ditch lining (riprap, geotextile fabric,plastic sheeting, etc.). Limit the length of a trench excavation to 500 feetat any one time (the excavated material should beplaced upgradient of the trench). If the collected runoff is contaminated with oil,grease, or other petroleum products, filteringthrough an oil/water separator or a filtrationmechanism is recommended. The DEP should becontacted for any significant known spill or unknownsource of contaminant.Avoid working in periods ofintense, heavy rain.12

Concrete wash water is alkaline and can contaminategroundwater or surface water. A containment structureshould be provided to retain, collect, and solidify concretebefore it can clog a drainage channel or structure. Concretewashouts are designed to promote the hardening of theconcrete and evaporation of excess liquids.CONSTRUCTION SPECIFICATIONS A concrete washout station should be sized tohandle all the wash water, solids and rainfallwithout overflowing. Typically, 7 gallons of water arerequired to clean a truck chute and 50 gallons forthe hopper of a concrete truck. A below-grade washout should be sized to containall liquid wastes with a 4-inch freeboard. Access to the washout pit should be stable andsecure (i.e. base of gravel or crushed rock). A washout facility should not be placed within 50feet of a storm drain or discharge point unless thepit is lined with anchored plastic sheeting (minimum10-mil thickness) and is not allowed to overflow.Inspect the structure on adaily basis to assess usageand identify leaks andbreaches. Dispose of thesolids appropriately.13SiteDevelopmentCONCRETE WASHOUTS

SiteDevelopmentSTOCKPILESStockpiled soils should be covered with an erosion controlcover, and a sediment barrier should be installed alongtheir downgradient edge to collect runoff and sediments. Insome situations, plastic sheeting or other material such aswoven or non-woven geotextile fabric may be used to coverstockpiles. Plastic sheeting should be polyethylene with aminimum thickness of 4 mils.CONSTRUCTION SPECIFICATIONS The soil surface should be smooth and free ofprotruding rocks and debris to prevent punctures ofa fabric cover. A fabric cover should be provided with 12 to 24-inchoverlaps in the direction of runoff. Anchoring should be continuous along each sideof the pile. On the windy side, additional anchorsshould be provided to maintain soil coverage and toprevent ballooning or blowouts. Topsoil from an agricultural source may be high innitrogen and phosphorus. Special care should betaken with a secure cover if stockpiled upslope froma sensitive resource.Inspect regularly andbefore, during and afterany major rain event.Repair as necessary.14

Sediment barriers should be installed downgradient of alldisturbed soils. There are many available types of sedimentbarriers provided they are installed, used, and maintainedproperly.IMPORTANT NOTE:Sediment barriers reduce runoff velocity and allow forsoil settlement. If water has a chance to concentrateand gain velocity, most sediment control barriers willfail. Water velocity is a critical element of erosion.COMPANION BMPs: Mulching, Vegetation,Riprap, Slopes and RoadsTwo rows of sediment barriers(i.e. silt fence and a bermof erosion control mix) maybe preferred for controllingsediment discharge near anatural resource, for largedisturbances or on steepslopes of wet loose soils.Sediment barriers shouldbe inspected and repairedbefore, during, and after eachrain event.15SedimentControlsB - SEDIMENT CONTROLS

CONSTRUCTION SPECIFICATIONSSedimentControls Sediment barriers should be installed prior to soildisturbance. All barriers should be installed on the land contourand each end curved uphill to prevent bypass (to anelevation higher than the top of the barrier). The runoff from the contributing area should notexceed the capacity of the barrier; or mid-slopebarriers may be necessary. The drainage flowlength should be no longer than 100 feet. Where possible, a level area immediately upgradient of the barrier should be provided forponding and absorption.Collected sediments shouldbe removed when one-halfthe height of the barrier isfilled.Damaged or otherwiseineffective sedimentbarriers should be replacedwith new material or adifferent barrier measure.16

Silt fence is a permeable geotextile fabric which interceptsoverland runoff, reduces flow velocity, and promotes thesettlement of sediments. The geotextile fabric will degradedue to sun exposure and its life span is approximately onefield season. Pre-manufactured silt fencing with attachedposts is used in most situations.CONSTRUCTION SPECIFICATIONS The fence should be anchored to resist pull-out,and be stretched tightly between stakes to preventsagging. A 6-inch wide and 6-inch deep trench should beexcavated upgradient of the fence line to key the“flap” of the fabric. The trench is backfilled andcompacted. When joints are necessary, filter cloth should bespliced by wrapping end stakes together. In areas where the flap cannot be keyed properly(due to frozen ground, bedrock, stony soil, roots,near a protected natural resource, etc.), the silt fenceshould be anchored with aggregate, crushed stone,erosion control mix, or other material.Silt fence can be difficultto install properly inshallow-to-ledge, stony,or forested soils as wellas frozen ground. Theadded disturbance neara water resource is notrecommended.17SedimentControlsSILT FENCE

SedimentControlsSilt fence should beremoved when the area isstabilized. The collectedsediments should beleveled, seeded andmulched.18

Berms of erosion control mix (ECM) are effective on frozenground, outcrops of bedrock, and heavily rooted forestedareas, or when other temporary erosion and sedimentcontrol measures are not practicable.IMPORTANT NOTE:A great source of erosion control mix is stumpgrindings. The soil within the root ball should not beremoved before grinding as it adds structure to themedia. See the Erosion Control Mix Mulch section formaterial specifications.CONSTRUCTION SPECIFICATIONS It may be necessary to cut, pack down or removetall grasses, brush or woody vegetation to avoidvoids and bridges that allow the washing away offine soil particles. The ECM berm should be a minimum of 12” highand a minimum of two feet wide. On longer orsteeper slopes, the will need to be wider and higher. Berms composed of ECM can be reshaped whennecessary.Depending upon the type ofmaterial, the berm may beplaced by hand, machinery, orpneumatic blower.19SedimentControlsEROSION CONTROL MIX BERM

FILTER SOCKSSedimentControlsA continuous contained berm or filter sock is a manufacturedsynthetic netting tube that is filled with erosion control mix, orother finely shredded organic material (i.e. coconut fiber orother). The netting prevents the displacement and loss of theorganic filter material. Continuous contained berms work wellin areas where trenching for a silt fence is not feasible suchas on frozen ground or over pavement. A filter sock can bereshaped (if a vehicle drives over it).Seeds may be added to the filler material for a permanentvegetation cover. Various manufactured products areavailable and installation should follow the manufacturer’sspecifications and type of media.CONSTRUCTION SPECIFICATIONS A filter sock’s most effective use is for smalldisturbed areas, as a perimeter protection arounda soil stockpile, or a sediment barrier in low flowdrainage swales or around drainage outlets andcatchbasins. Full contact with the ground is critical to preventshort circuiting under the tube and the groundsurface should be smooth and level. In woodedareas, protruding roots and debris may need to beremoved; and in grassed areas, the grass needs tobe either mowed or compressed down. Staking may be necessary on steep slopes. Upon final stabilization, the tube can be cut openand the material spread out onto the ground. Themesh material should be removed.20

SedimentControlsContinuous containedberms may be placed byhand, machinery or thesock may be filled on-siteby a pneumatic blower.21

STONE CHECK DAMSSedimentControlsStone check dams are constructed across a swale ordrainage ditch to reduce the flow velocity and erosive forcesand to promote the deposit of sediments. Stone check damsare most important in channels with a slope greater than 6%.They are not effective for silts and clays. Other proprietaryproducts are available and should be used and installed perthe manufacturer’s guidelines.IMPORTANT NOTE:Check dams are intended for the settlement ofsediments and flow velocity reduction. A ditch lining willbe necessary for erosion control.CONSTRUCTION SPECIFICATIONS Check dams should be installed before runoff isdirected to the swale. The area around each check dam should be free ofdebris. A stone check dam should be comprised of wellgraded crushed rock with a maximum size of 6inches and

this handbook is to help land developers, consultants, and contractors use the appropriate erosion and sedimentation control Best Management Practices (BMPs) for the site and conditions whenever disturbing soil or removing a natural ground cover.