1、Designation: D 7208 06Standard Test Method forDetermination of Temporary Ditch Check Performance inProtecting Earthen Channels from Stormwater-InducedErosion1This standard is issued under the fixed designation D 7208; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the guidelines, requirements,and procedures fo
3、r evaluating the ability of temporary ditchchecks to protect earthen channels from stormwater-inducederosion. Critical elements of this protection are the ability ofthe temporary ditch check to:1.1.1 Slow and/or pond runoff to encourage sedimentation,thereby reducing soil particle transport downstre
4、am;1.1.2 Trap soil particles up stream of structure; and1.1.3 Decrease soil erosion.1.2 This test method utilizes full-scale testing procedures,rather than reduced-scale (bench-scale) simulation, and ispatterned after conditions typically found on construction sitesat the conclusion of earthwork ope
5、rations, but prior to the startof revegetation work. Therefore this test method considers onlyunvegetated conditions.1.3 This test method provides a comparative evaluation of atemporary ditch check to baseline bare soil conditions undercontrolled and documented conditions.1.4 The values stated in SI
6、 units are to be regarded asstandard. The inch-pound units given in parentheses areprovided for information purposes only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-
7、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Also, the user mustcomply with prevalent regulatory codes, such as OSHA (Oc-cupational Health and Safety Administration) guidelines, whileusing the test method.2. Referenced Documents2.1 ASTM
8、Standards:2D 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12,400 ft-lbf/ft3(600kN-m/m3)D 6460 Test Method for Determination of Erosion Control(ECB) Performance in Protecting Earthen Channels fromStormwater-Induced Erosion3. Terminology3.1 Definition of T
9、erm Specific to This Standard:3.1.1 temporary ditch check (in erosion control), nanon-permanent barrier consisting of rocks, straw bales, excel-sior logs, wattles, lumber, rock bags, interlocking pre-castconcrete blocks, or other materials installed or constructedacross a drainage way, swale, or oth
10、er ephemeral waterway toreduce flow velocity, decrease erosion, and promote soilretention.4. Summary of Test Method4.1 The performance of a temporary ditch check in reducingstormwater-induced erosion is determined by subjecting thematerial to simulated stormwater flow in a controlled anddocumented e
11、nvironment.4.2 Key elements of the testing process include:4.2.1 Calibration of the stormwater simulation equipment;4.2.2 Preparation of the test channel;4.2.3 Documentation of the temporary ditch check(s) to betested;4.2.4 Installation of the temporary ditch check(s);4.2.5 Performance of the test;4
12、.2.6 Collection of hydraulic, topographical, and associateddata;4.2.7 Analysis of the resultant data; and4.2.8 Reporting.5. Significance and Use5.1 This test method evaluates temporary ditch checks andtheir means of installation to:5.1.1 Reduce soil loss and sediment concentrations instormwater runo
13、ff under conditions of varying channel condi-tions and soil type; and1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.25.08 on SedimentControl.Current edition approved May 15, 2006. Published July 2006.2For referenc
14、ed ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
15、nshohocken, PA 19428-2959, United States.5.1.2 Improve water quality exiting the area disturbed byearthwork activity by reducing suspended solids.5.2 This test method models and examines conditions typi-cally found on construction sites involving earthwork activi-ties, including: highways and roads;
16、 airports; residential, com-mercial and industrial developments; pipelines, mines, andlandfills; golf courses; etc.5.3 This test method is a performance test. It is a compara-tive tool for evaluating the erosion control characteristics ofdifferent temporary ditch checks and can be used for qualityco
17、ntrol to determine product conformance to project specifi-cations. Take caution when comparing results from differentlaboratories because information about between-laboratoryprecision is incomplete and slight differences in soil and otherenvironmental and geotechnical conditions may affect tempo-rar
18、y ditch check performance. Unique project-specific condi-tions should be taken into consideration.6. Apparatus6.1 Water Delivery SystemThe water delivery systemshall include pump(s), piping, channels, and water controlstructures, as necessary, to achieve the desired hydraulicconditions. The water co
19、ntrol structures shall regulate the flowand to direct it into the desired test channel. The water deliverysystem shall be constructed such that turbulence at the entranceto the test channel is minimized. Use of flow straighteners (forexample, tube racks or vanes) are recommended to reduceturbulence
20、and achieve uniform flow conditions. A direct flowsystem (that is, controlled flow diverted from a natural water-way) may also be employed for this purpose. The waterdelivery system in Fig. 1 shows an example of a closed-loopwater delivery system.6.2 Water SourceAny water source shall be suitable fo
21、rthis use provided that it is not sediment laden or containsdeleterious materials that could impair the operation of thepumps.6.3 Total Station SystemThe total station system is astandard surveying instrument that is capable of measuringvertical and horizontal angles, and distance, simultaneously to
22、determine measurement point coordinates (that is, X, Y and Zaxis) and that uses an internal data logger to store thisinformation for future use. In lieu of a total station system,manual surveying equipment may be used provided thatequivalent accuracy is achievable. Periodic calibration andcertificat
23、ion of this equipment shall be performed.6.4 Velocity ProbeA velocity probe capable of measuringpoint velocities to an accuracy of 6 0.03 m/s (0.1 ft/s) shall beused to identify flow conditions during test operation. Accept-able types of probes include electromagnetic, spinning cup,propeller, and st
24、atic tube devices. Periodic calibration andcertification of this equipment shall be performed.6.5 MiscellaneousOther miscellaneous equipment in-cludes: meteorological equipment (wind speed, temperature,precipitation), and cameras or video recorders.7. Procedure7.1 Test Channel Preparation:7.1.1 Cons
25、truct earthen test channels using conventionalearthwork placement techniques similar to procedures outlinedin Test Method D 6460. Perform compaction of channel bedmaterial to create a stable subgrade.7.1.2 Plate the channel surface with a minimum 45 cm (18in) thick veneer of soil. General soil types
26、 to be used for testingshall be loam, clay, and sand. Target grain sizes and plasticityindices are included in Table 1. Place the veneer in 15 cm (6 in)FIG. 1 Typical Closed Looped Water Delivery SystemD7208062lifts and compact to 90 6 3 % of standard Proctor density inaccordance with Test Method D
27、698.7.1.3 Excavate the channels to a trapezoidal cross-sectionwith a 0.61 m (2 ft) bottom width and 2H:1V side slopes. Thetest channels shall be a minimum of 18.3 m (60 ft) in length toallow sufficient distance between temporary ditch check struc-tures during testing. Bed slope shall be approximatel
28、y 5 %. Fig.2 shows a typical channel profile and Fig. 3 shows a typicalchannel cross-section.7.1.4 Begin the test reach far enough below the inlet to thechannel to ensure flow is uniform and extend 12.2 m (40 ft)downstream from that point. Establish benchmarks on eitherside of the channel at each en
29、d of the test reach and at 1.5 m(5 ft) intermediate intervals (nine cross-sections total).7.1.5 Loosen the soil veneer in the test reach and 1.5 m (5ft) upstream and downstream of the test reach to a depth ofapproximately 10 cm (4 in.) using a tiller or other appropriatetools. Rake the tilled channe
30、l smooth with a steel hand rake andcompact. Repair depressions, voids, soft or uncompacted areasbefore testing can commence. Also, free the channel fromobstruction or protrusions, such as roots, large stones or otherforeign material.7.1.6 If the channel has been used previously for a testseries, dis
31、card the soil carried out of the channel, and obliterateany rills and gullies. Spread new soil of the same type acrossthe channel and blend (rake or tilled) into the surface.7.2 Calibration:7.2.1 Perform determination of the water delivery systemdischarge (Q). Begin calibration of the water delivery
32、 systemwhen a steady-state flow is achieved.7.2.2 For open-channel water delivery systems, measure thedepth of water flowing into the test channel. Measure thevelocity in the supply channel using the velocity probe in thethree-point measurement pattern shown in Fig. 3.7.3 Pre-Test Documentation:7.3.
33、1 Maintain a test folder for each test cycle, includinginformation on:7.3.1.1 Site conditions;7.3.1.2 Geotechnical and soil conditions;7.3.1.3 Meteorological data;7.3.1.4 Temporary ditch check product type, description,and installation procedure; and7.3.1.5 Photo documentation.7.3.2 Include the foll
34、owing subjective site information:general visual conditions of the channel to be tested; generalmeteorological information; channel treatment; photographsand/or videotape, and any supplemental information that is notincluded in the following sections, but is thought to be ofsignificance to the test.
35、7.3.3 Include the following geotechnical and soils informa-tion: soil classification Unified Soil Classification System(USCS) and USDA classification system.; standard proctormoisture-density relationship; “K” factor; and; gradation (in-cluding hydrometer test for the P200fraction).7.3.4 Include the
36、 following meteorological information: alldata from the on-site weather station at the time of the test (thatis, ambient air temperature, wind speed and precipitation).7.3.5 Include the following product type and descriptioninformation: manufacturer name; product name; description;specifications; si
37、ze, and; a sample of the material, if practical.7.4 Test Set-Up:7.4.1 Install the temporary ditch check(s) in the channelafter calibration has been completed and the test channel hasbeen prepared. Document the installation methodology for thetemporary ditch check(s) including: orientation on the bed
38、 andside slopes (longitudinal or lateral); placement (which sidefaces up); termination details; joint details; spacing betweentemporary ditch checks if more than one is to be tested, and;anchor type and installation pattern. Place the temporary ditchcheck(s) across the channel bottom perpendicular t
39、o the flowdirection and extend it up the side slopes far enough so pondedwater cannot erode around the temporary ditch check. If morethan one temporary ditch check is to be tested, spacing shallfollow manufacturer recommendations or ditch check spacingequation (see Section 8).7.4.2 Measure the eleva
40、tion of the channel surface with thetotal station equipment using the reference benchmarks and aTABLE 1 Target Grain Sizes and Plasticity IndicesSand Loam ClayD100(mm) D10040 D10025 D10010D85(mm) 1.0 D8510.0 0.5D855.0 0.01D851.0D50(mm) 0.08 D502.0 0.01D501.0 0.001D500.1D15(mm) 0.001 D150.0005 D15D15
41、 0.0005Plasticity Index nonplastic 1 PI 8 14 PIFIG. 2 Typical Channel ProfileD7208063stringline between opposing benchmarks. Take elevation mea-surements for each test cross-section (nine total) at the loca-tions shown in Fig. 3. Elevation measurements for additionalcross-sections directly in front
42、and behind each temporaryditch check shall also be taken to measure deposition and/orscour directly adjacent to ditch check structure. To allowmeasurement of the channel surface, a 0.6 cm (0.25 in.)diameter steel tip extension (“stinger”) may need to be attachedto the base of the surveyors rod. Perf
43、orm rod placement froman above channel platform, so that the rodman does not walkon the test channel. The rodman must use care in positioningthe rod so measurements are indicative of the channel surface.7.4.3 Take photographs and/or videotape of the test channelprior to testing.7.5 Test Operation an
44、d Data Collection:7.5.1 Include the following test data: operator name andtitle; time flow began; time flow stopped; time runoff stopped;flow depths, and; measured velocities.7.5.2 Take water surface elevation measurements at thecenterline point of each test cross-section and directly in frontand be
45、hind each temporary ditch check using the total stationequipment as soon as the flow reaches a steady-state, uniformcondition. Take velocity measurements at the centerline pointof each test cross-section using the velocity probe (see Fig. 3).If the depth of flow is less than 20 cm (8 in.), take only
46、 thesix-tenths depth reading. Take photographs and/or videotapeduring the test.7.5.3 Perform testing at a target flow of 0.085 m3/s (3 cfs).7.5.4 Test duration shall be 30 minutes or until a temporaryditch check becomes dislodged.7.5.5 At the conclusion of the test, take channel surfaceelevation mea
47、surements again at the same locations as thepre-test measurements. As with the previous test data collec-tion, take the rodman elevation measurements from above anddo not walk on the test channel surface.7.5.6 Record general observations regarding the conditionof the tested temporary ditch check(s)
48、at the conclusion of thedata collection.7.5.7 Carefully remove the temporary ditch check(s) fromthe channel, with as little disturbance of the soil as possible.Note general observations regarding the condition and scourpatterns. Take photographs and or videotape to record thecondition of the test ch
49、annel. Markers may be used to identifyany scour patterns for the pictorial documentation.7.5.8 Include a minimum of three tests for each type oftemporary ditch check to be evaluated.8. Calculation8.1 Calibration Data:8.1.1 DischargeCalculate discharge for each flow andreport measurement method and the associated accuracy.8.2 Temporary Ditch Check Spacing:8.2.1 Ditch Check Spacing EquationThe necessary spac-ing required between temporary ditch checks that place thebottom of the upstream temporary ditch check and the top ofthe downstream temporary ditch check at the same elev
