Construction Sediment:Construction Sediment:The Greatest Threat to Water QualityThe Greatest Threat to Water Quality

Raymond Slade, Jr.,Raymond Slade, Jr., Certified Professional HydrologistCertified Professional Hydrologist

Organization of presentationOrganization of presentation

• IntroductionIntroduction--how construction sediment contaminates water --how construction sediment contaminates water resourcesresources

• The ThreatThe Threat--why construction sediment is the greatest threat --why construction sediment is the greatest threat to water qualityto water quality

• Contamination ExamplesContamination Examples--Central Texas examples of --Central Texas examples of water resource contamination from construction sedimentwater resource contamination from construction sediment

• Local ControlsLocal Controls--construction controls most used in Texas--construction controls most used in Texas

• Available ControlsAvailable Controls--construction controls used throughout --construction controls used throughout the U.S.the U.S.

• Model OrdinancesModel Ordinances--existing and model construction --existing and model construction sediment ordinancessediment ordinances

• Additional InformationAdditional Information--references and sources for more --references and sources for more informationinformation

Beginning of each section designated by blue type at top of slideBeginning of each section designated by blue type at top of slide

IntroductionIntroduction Construction typically involves building highways, roads, structures, Construction typically involves building highways, roads, structures,

parking lots, utility lines, and work access roads. Soils are disturbed parking lots, utility lines, and work access roads. Soils are disturbed and vegetation often removed during construction. Many tons of and vegetation often removed during construction. Many tons of loose sediment typically are created during this process.loose sediment typically are created during this process.

Rainfall and wind then often transport tons of sediment to Rainfall and wind then often transport tons of sediment to receiving streams, reservoirs, and aquifers, causing water receiving streams, reservoirs, and aquifers, causing water quality degradation. Additionally, vegetation attenuates much quality degradation. Additionally, vegetation attenuates much of the contaminants in overland flow, thus its removal causes of the contaminants in overland flow, thus its removal causes additional water-quality degradation of receivingadditional water-quality degradation of receiving streams.streams.

Because of the facts presented on the Because of the facts presented on the next 5 slidesnext 5 slides, , many earth scientists, including the author of this many earth scientists, including the author of this

presentation, deem construction sediment to represent presentation, deem construction sediment to represent the greatest single threat to water resources.the greatest single threat to water resources.

Sediment in Barton Creek flood Sediment in Barton Creek flood through Barton Springs poolthrough Barton Springs pool

The ThreatThe Threat

Threat 1.Threat 1. Sediment is the only water-quality Sediment is the only water-quality contaminant that exists throughout all stream basins. contaminant that exists throughout all stream basins. Within a few hours, a single small construction site can Within a few hours, a single small construction site can generate a sediment load sufficient to contaminate generate a sediment load sufficient to contaminate entire receiving streams, lakes, and aquifers.entire receiving streams, lakes, and aquifers.

Sediment from constructionSediment from construction of motel on Lady Bird Lakeof motel on Lady Bird Lake

Threat 2.Threat 2. Along with sediment, typical construction site Along with sediment, typical construction site pollutants include fluids from construction equipment, pollutants include fluids from construction equipment, adhesives, paints, cleaners, masonry, cement, fertilizers, adhesives, paints, cleaners, masonry, cement, fertilizers, pesticides, and wastes from electrical, plumbing, heating, pesticides, and wastes from electrical, plumbing, heating, and air conditioning installations.and air conditioning installations.

Bee Cave Galleria in Bee Cave Galleria in Barton Creek basinBarton Creek basin

Pesticide washed into Pesticide washed into creek from improperly creek from improperly stored bagsstored bags

Dead fish in Dead fish in receiving streamreceiving stream

Example of pesticides in runoff from Example of pesticides in runoff from Bee Cave Galleria development in the Bee Cave Galleria development in the Barton Creek basin.Barton Creek basin.

Threat 3.Threat 3. Many studies throughout the Nation Many studies throughout the Nation document sediment loads to be as much as 1000 times document sediment loads to be as much as 1000 times greater from construction sites than from static land greater from construction sites than from static land use sites.use sites.

Threat 4.Threat 4. Degradation of water quality from Degradation of water quality from construction sediment often is severe enough to limit construction sediment often is severe enough to limit or even prohibit water use and often kills biological or even prohibit water use and often kills biological species and vegetation in receiving waters.species and vegetation in receiving waters.

Sediment Sediment plumeplume

Threat 5.Threat 5. Expensive remedial action sometimes can Expensive remedial action sometimes can remove sufficient volumes of deposited and remove sufficient volumes of deposited and suspended sediment in order to restore limited water suspended sediment in order to restore limited water use. However preventive action usually is much use. However preventive action usually is much cheaper than remedial action and aquifers and many cheaper than remedial action and aquifers and many ponds and reservoirs cannot be restored. ponds and reservoirs cannot be restored.

Dredging and pumping Dredging and pumping to remove sedimentto remove sediment

Removing deposited Removing deposited sediment from streamsediment from stream

Construction site runoffConstruction site runoffEnvironmental ImpactsEnvironmental Impacts

• Transports toxic pollutants and nutrientsTransports toxic pollutants and nutrients• Turbidity limits sunlight penetration and Turbidity limits sunlight penetration and

photosynthesisphotosynthesis• Reduces oxygen availabilityReduces oxygen availability• Clogs fish gillsClogs fish gills• Fills spawning and breeding groundsFills spawning and breeding grounds• Smothers bottom CommunitiesSmothers bottom Communities• Reduces visibility for feeding and upsets food chainReduces visibility for feeding and upsets food chain

Effect of erosion and sediment controls on Effect of erosion and sediment controls on suspended sediment concentrationssuspended sediment concentrations

Construction site conditionConstruction site conditionData from Piedmont, Ca.

A BMP is a “Best A BMP is a “Best Management Practice”Management Practice”

Dozens of studies throughout the Nation document Dozens of studies throughout the Nation document erosion rates from erosion rates from natural areasnatural areas (established urban, (established urban, forest, rangeland) to be less than forest, rangeland) to be less than 1.01.0 ton per acre per ton per acre per year.year.

Many dozens of other studies document erosion from Many dozens of other studies document erosion from construction sitesconstruction sites to range from to range from 7.27.2 to greater than to greater than 1,0001,000 tons per acre per year. tons per acre per year.

--EPA 840-B-92-002 --EPA 840-B-92-002

reportreport

Central Texas examples of water resource Central Texas examples of water resource contamination from construction sedimentcontamination from construction sediment

The following slides present 5 examples where construction The following slides present 5 examples where construction sediment has contaminated streams, ponds, and springs in sediment has contaminated streams, ponds, and springs in Central Texas. For each example, the construction site Central Texas. For each example, the construction site represented only a very small part of the watershed area that represented only a very small part of the watershed area that provides runoff to the contaminated site. Each of these provides runoff to the contaminated site. Each of these instances of sediment contamination could have been instances of sediment contamination could have been prevented with proper control measures.prevented with proper control measures.

Contamination ExamplesContamination Examples

Throughout much of 1980, Throughout much of 1980, sediment in runoff from the sediment in runoff from the construction of Barton Creek construction of Barton Creek Square Mall entered Barton Square Mall entered Barton Creek and discharged from Creek and discharged from Barton Springs within hours of Barton Springs within hours of many rainfall events. The many rainfall events. The sediment concentrations at the sediment concentrations at the Springs were so great that the Springs were so great that the springs pool had to be closed springs pool had to be closed during such events.during such events.

Sediment in water sample Sediment in water sample from Barton Springsfrom Barton Springs

The mall covers about ¼ square mile The mall covers about ¼ square mile and Barton Springs flow comes from and Barton Springs flow comes from about 350 square miles yet about 350 square miles yet construction sediment from the mall construction sediment from the mall was so great that visibility in the was so great that visibility in the pool approached zero. pool approached zero.

Measure of turbidity from sediment during storm

Barton SpringsBarton Springs

Lick CreekLick Creek

Green Hole on Lick Creek, West Green Hole on Lick Creek, West Travis County, Summer 2003Travis County, Summer 2003

Green Hole on July 27, 2004, Green Hole on July 27, 2004, after rainfall caused overflow after rainfall caused overflow from the West Cypress Hills from the West Cypress Hills subdivision detention pond for subdivision detention pond for development constructiondevelopment construction

Dead Mans Hole on Dead Mans Dead Mans Hole on Dead Mans Creek, North Hays County, before Creek, North Hays County, before construction of a small dam in construction of a small dam in the watershed in Spring 2005the watershed in Spring 2005

Dead Mans Hole after Dead Mans Hole after construction of the damconstruction of the dam

Dead Mans CreekDead Mans Creek

Hamilton Pool, West Travis County,Hamilton Pool, West Travis County,prior to June 2007prior to June 2007

Road cut for land development in Road cut for land development in Hamilton Creek basin began June, 2007Hamilton Creek basin began June, 2007

Hamilton CreekHamilton Creek

Hamilton Creek (cont.)Hamilton Creek (cont.)

Road cut along Hamilton Creek Road cut along Hamilton Creek

Hamilton Pool after a small Hamilton Pool after a small storm flushed construction storm flushed construction sediment to the poolsediment to the pool

Bee CreekBee Creek

Bee Creek near Hwy 71, West Travis County, prior to development in basin

Bee Creek, August 2007, immediately after development began in basin

Construction controls most used in TexasConstruction controls most used in TexasSilt fences which often fail during large stormsSilt fences which often fail during large storms

Local ControlsLocal Controls

April 2007 photograph of sediment-saturated runoff from the April 2007 photograph of sediment-saturated runoff from the AMD construction site, fouling stream waters with mud that AMD construction site, fouling stream waters with mud that was supposed to be stopped by a silt fence was supposed to be stopped by a silt fence

Could this be the next construction sediment problem?Could this be the next construction sediment problem?

Construction of the Rocky Creek Ranch subdivision on the south side of Construction of the Rocky Creek Ranch subdivision on the south side of Hamilton Pool Road about 4.5 miles west of Highway 71. The photo shows Hamilton Pool Road about 4.5 miles west of Highway 71. The photo shows the clearing, cutting and filling pursuant to the first phase of development the clearing, cutting and filling pursuant to the first phase of development on the east side of Rocky Creek (a tributary of Barton Creek). on the east side of Rocky Creek (a tributary of Barton Creek). June 2008 photoJune 2008 photo

A better silt fenceA better silt fence

www.stormwatercenter.net/Slideshows/ESC.htm

Available controlsAvailable controlsConstruction controls used throughout the U.S.Construction controls used throughout the U.S.

1. Minimize Clearing1. Minimize Clearing2.a. Protect Waterways2.a. Protect Waterways Buffers and special crossings for waterwaysBuffers and special crossings for waterways2.b. Stabilize Drainageways2.b. Stabilize Drainageways Checkdams, sod, erosion control blankets, rip rap Checkdams, sod, erosion control blankets, rip rap 3. Phase Construction3. Phase Construction4. Rapid Soil Stabilization4. Rapid Soil Stabilization hydroseed, mulch, erosion control blanketshydroseed, mulch, erosion control blankets5. Protect Steep Slopes5. Protect Steep Slopes6. Perimeter Controls6. Perimeter Controls Earth dikes, diversions, silt fences, stabilize construction entranceEarth dikes, diversions, silt fences, stabilize construction entrance7. Employ Advance Settling Devices7. Employ Advance Settling Devices sediment traps & sediment basinssediment traps & sediment basins8. Certified Contractors Implement Plan8. Certified Contractors Implement Plan9. Adjust Plan as Field Conditions change9. Adjust Plan as Field Conditions change10. Assess and Revise Practices After Storms10. Assess and Revise Practices After Storms Repair damage, modify practices, reinforce, cleanoutRepair damage, modify practices, reinforce, cleanout

http://www.stormwatercenter.net/Slideshows/ESC.htmhttp://www.stormwatercenter.net/Slideshows/ESC.htm

Note: Most of these practices are not commonly used in Texas

Available sediment construction controlsAvailable sediment construction controls Slope protection Slope protection hay mulchinghay mulching

Hydroseeding operationHydroseeding operationHay mulch Hay mulch ground coverground cover

Use of mats to minimize erosion Use of mats to minimize erosion

Available sediment construction controls (cont.)Available sediment construction controls (cont.)

Sedimentation basin Sedimentation basin with standpipewith standpipe

CheckdamsCheckdams

Berm dividing multi-cell Berm dividing multi-cell sedimentation basinsedimentation basin

Available sediment construction controls (cont.)Available sediment construction controls (cont.)

Swale to divert runoff Swale to divert runoff around construction site around construction site in non-erosive mannerin non-erosive manner

Mats and hay to stabilize channel Mats and hay to stabilize channel

Rock to stabilize channelRock to stabilize channel

Bonded Fiber MatrixBonded Fiber MatrixBonded Fibre Matrix has been reported to be a very effective product for Bonded Fibre Matrix has been reported to be a very effective product for controlling erosion, especially on steep slopes. It is a unique class of controlling erosion, especially on steep slopes. It is a unique class of hydroseeding erosion control product, a hydraulically applied product that erosion control product, a hydraulically applied product that does the job as well as or better than erosion control blankets. The matrix is does the job as well as or better than erosion control blankets. The matrix is a continuous layer of elongated fiber strands held together by a water-a continuous layer of elongated fiber strands held together by a water-resistant bonding agent. It keeps raindrops from hitting the soil because it resistant bonding agent. It keeps raindrops from hitting the soil because it has no holes larger than one millimetre. It allows no gaps between the has no holes larger than one millimetre. It allows no gaps between the product and the soil. It has a high water-holding capacity. It will not form a product and the soil. It has a high water-holding capacity. It will not form a water-insensitive crust that can inhibit plant growth. It biodegrades into water-insensitive crust that can inhibit plant growth. It biodegrades into materials that help plant growth (Wikipedia).materials that help plant growth (Wikipedia).

Model OrdinancesModel Ordinances

EExisting and model construction sediment ordinancesxisting and model construction sediment ordinances

Many cities, counties, states and other governmental agencies have Many cities, counties, states and other governmental agencies have adopted ordinances that address all aspects of contamination from adopted ordinances that address all aspects of contamination from construction. Many such ordinances are presented by the Stormwater construction. Many such ordinances are presented by the Stormwater

Center at Center at http://www.stormwatercenter.net/ Click on “ordinance” on left side of pageClick on “ordinance” on left side of page

Selected recommendations for construction Selected recommendations for construction sediment control in the Hill Country Areasediment control in the Hill Country Area

• A phased plan for simultaneous construction should be prepared and A phased plan for simultaneous construction should be prepared and approved by a licensed engineer or other specialistapproved by a licensed engineer or other specialist

• The size of the disturbed area under construction should be no greater The size of the disturbed area under construction should be no greater than that for which sediment in runoff from a 10-year storm would be than that for which sediment in runoff from a 10-year storm would be contained on site.contained on site.

• A licensed engineer or other specialist should design and approve the A licensed engineer or other specialist should design and approve the plan and practices for construction sediment control to assure the plan and practices for construction sediment control to assure the above.above.

• A licensed engineer or other specialist should be responsible for A licensed engineer or other specialist should be responsible for inspection and maintenance of the construction sediment controls inspection and maintenance of the construction sediment controls and plan throughout the construction period.and plan throughout the construction period.

The Stormwater Center presents a model ordinanceThe Stormwater Center presents a model ordinance for controlling construction sediment atfor controlling construction sediment at

http://www.stormwatercenter.net/Model%20Ordinances/esc_model_ordinance.htm

I.  Introduction/ PurposeI.  Introduction/ PurposeII. DefinitionsII. Definitions PermitsPermits Review and ApprovalReview and Approval Erosion and Sediment Control PlanErosion and Sediment Control PlanIII. Design RequirementsIII. Design Requirements Clearing and GradingClearing and Grading Erosion ControlErosion Control Sediment ControlsSediment Controls Waterways and WatercoursesWaterways and Watercourses Construction Site AccessConstruction Site AccessIV. InspectionIV. InspectionV. EnforcementV. Enforcement Stop-Work Order; Revocation of PermitStop-Work Order; Revocation of Permit Violation and PenaltiesViolation and Penalties

Major components of the ordinance:Major components of the ordinance:

Another model ordinance for erosion control is presented Another model ordinance for erosion control is presented on the Internet by the EPA aton the Internet by the EPA at

http://www.epa.gov/owow/nps/ordinance/mol2.htm

Keeping Soil in Its Place:Keeping Soil in Its Place: A Presentation on Erosion andA Presentation on Erosion and

Sediment Control (ESC)Sediment Control (ESC)is online atis online at

http://www.stormwatercenter.net/Slideshows/ESC.htm

Additional InformationAdditional InformationReferences and sources for more information

Slideshows with additional information on Slideshows with additional information on stormwater managementstormwater management

• Why watersheds Why watersheds http://www.cwp.org/whywatersheds_files/frame.htm

• Impacts of urbanization Impacts of urbanization http://www.stormwatercenter.net/Slideshows/impacts%20for%20smrc/sld001.htm

• Better site design Better site design http://www.stormwatercenter.net/Slideshows/bsd%20for%20smrc/sld001.htm

• Eight tools for watershed protection Eight tools for watershed protection http://www.stormwatercenter.net/Slideshows/8tools%20for%20smrc/sld001.htm

• Stormwater Best Management Practices Stormwater Best Management Practices http://www.stormwatercenter.net/Slideshows/smps%20for%20smrc/sld001.htm