1、Designation: C1746/C1746M 12Standard Test Method forMeasurement of Suspended Sediment Removal Efficiency ofHydrodynamic Stormwater Separators and UndergroundSettling Devices1This standard is issued under the fixed designation C1746/C1746M; the number immediately following the designation indicates t
2、heyear of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method concerns measurement of the effi
3、-ciency of hydrodynamic separators and underground settlingdevices in removing suspended sediment from simulatedstormwater runoff under conditions defined herein. This testmethod is not intended for use in determining field removalefficiency.1.2 Units tested shall be of a size commonly manufactured,
4、not a scale model. This test method is not intended to addressproduct scaling.1.3 This test method is not for measuring the removalefficiency of filters or the scouring potential of hydrodynamicseparators and underground settling devices.1.4 In this test method, only gravity flow operation isaddress
5、edperformance of units operating under pressurizedconditions is not addressed.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the
6、other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 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-priate safety and health practi
7、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D422 Test Method for Particle-Size Analysis of SoilsD854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD4959 Test Method for Determination of Water (Moisture)Co
8、ntent of Soil By Direct HeatingE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 inlet (or outlet) rounding, nradius of fillet at insidepipe junction with separator structure.4. Summary of Test Method4.1 This test m
9、ethod describes procedures and equipment tomeasure the suspended sediment removal efficiency of hydro-dynamic separators and underground settling devices used fortreating stormwater runoff.5. Significance and Use5.1 Each device has unique flow patterns and turbulencecharacteristics and may exhibit a
10、 wide range of efficiencies asdischarge, particle-size distribution, particle density, and flowviscosity (that is, water temperature) changes. The testingprocedures described in Section 8 provide a method of mea-suring the removal efficiency of these devices under a givenflow condition, flow viscosi
11、ty (water temperature), andparticle-size distribution and density. Therefore, the results oftesting represent the flow, viscosity, and particle-size distribu-tion tested.6. Apparatus6.1 The experimental setup includes an influent straight pipe(without bends or fittings) of minimum length equivalent
12、to tenpipe diameters or 6 m 20 ft, whichever is less, upstream fromthe test unit and effluent pipe length equivalent to three pipediameters with a free-fall condition at its downstream end. Pipeshall have a Mannings roughness coefficient not greater than0.013.6.2 The test unit shall be set up to ref
13、lect actual fieldinstallation parameters to the greatest degree possible, includ-ing inlet/outlet roundings as supplied or recommended by themanufacturer.1This test method is under the jurisdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27
14、.70 onPrecast Concrete Products for Stormwater Management.Current edition approved June 15, 2012. Published July 2012. DOI: 10.1520/C1746_C1746M-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
15、ds volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.3 Influent and effluent pipe diameters shall be the mini-mum size recommended by the manufacturer
16、 and shall bedocumented in test results, as well as pipe orientation and pipeslopes (2 to 3 %).6.4 The sediment injection point shall be at the crown of theinfluent pipe at a distance equal to 2 6 0.1 pipe diametersalong the centerline of the pipe upstream of the inlet to thetreatment device to supp
17、ly the sediments in the simulatedstormwater runoff.6.5 The sediment delivery system (feeder) shall be com-prised of suitable means of sediment addition so as to provideconsistent sediment feed rate of solids (including an auger,vibratory hopper, well-mixed slurry injection system, or other).6.6 Aflo
18、w meter shall be installed to measure the water flowrate through the test unit.6.7 All components of the experimental setup shall beinspected immediately before any testing to confirm that nodamage or obstruction is present and that there are no sedi-ments or other deleterious materials therein. No
19、leakage insystem piping or from the unit is allowed during the test.7. Sampling7.1 Sampling of the sediment delivery system is intended toquantify the average influent concentration. Six feed ratesamples shall be taken from the feeder at of the injection point,at evenly spaced intervals over the tot
20、al duration of the test.Each sample shall be collected in a clean preweighed plastic1-L1.06-qt container over an interval timed to the nearest 1 s.7.2 Feed rate samples shall be a minimum 100 cm36.10in3 or collection interval shall not exceed 1 min, whichevercomes first. Samples shall be dried, weig
21、hed to the nearest 1 g0.002 lb and recorded. The feed rate coefficient of variation(COV) shall not exceed 0.10.7.3 The influent concentration of each sample shall becomputed from Eq 1:Cinf5WsampleD tQ g(1)where:Cinf= influent concentration,Wsample= dry weight of each sample,Q = measured flow rate,Dt
22、 = sampling duration,g = gravitational acceleration.8. Procedure8.1 Suspended Solids:8.1.1 The specific gravity of the particles shall be assessedbefore the test using Test Method D854. The particle-sizedistribution shall be determined according to Test MethodD422 using standard sieves conforming to
23、 Specification E11.8.1.2 For each test, a minimum of 10 kg 22 lb of materialshall be fed into the influent pipe. The suspended solidsconcentration shall be within the range of 50 to 300 mg/L8.3510-4to 2.50 10-3lb/gal as determined from feed ratesampling in 7.1.8.1.3 “Recirculated” water that passes
24、through the test unitshall not be redirected into the system until it has been filteredcompletely through a 53-m (270 US mesh) or finer filter (Note1) such that it is indistinguishable from the original water forthe purposes of this test.NOTE 1If feed material contains fractions less than 75 m 0.003
25、 in.,recirculated water shall be filtered through a 25-m (550 US mesh) filter.8.1.4 If river water is used, the river intake shall be highenough above the riverbed such that no inorganic materials arewithdrawn from the river.8.1.5 Water routed only once through the system, or “flow-through” water (t
26、hat is, river water), shall elicit a backgroundsediment concentration test. The background concentration testshall consist of running water through the device at 10 % of themaximum tested flow rate without feeding any sediments intothe system for a period of 1 h. After the 1-h period, the deviceshal
27、l be drained and the solids removed by the device shall becollected, dried, and sieved as described in 8.3. If the particlesare very small, that is, smaller than 53 microns, then theconcentration should be determined from hydrometer analysis.The background concentration for each particle size shall
28、thenbe estimated using the formula:C 5WtQg(2)where:C = background concentration,t = duration,W = weight of the measured solids,g = gravity, andQ = flow rate set at 10 % of the maximum tested flow rate.8.1.6 For computing the removal efficiency of a particlesize, the background concentration of that
29、particle size shall beadded to the feeding concentration of each test.8.1.7 Test flow shall be measured, maintained, and recordedat a defined constant rate and shall vary by no more than 3 %throughout the test.8.2 Water TemperatureTests shall be run at 18 to 23C 64to 74F. See Note 2.At a minimum, wa
30、ter temperatures in thesump of the test unit shall be recorded three times, at thebeginning, the middle, and the end of each test. The averagetemperature shall be used in data reporting.NOTE 2Tests may be run outside of specified temperature range witha clearly stated deviation from the test method
31、included in results(explicitly indicate temperatures as tested).8.3 Test Procedure:8.3.1 Dry and determine moisture content of a well-mixedfeed sample in accordance with Test Method D4959. Cool thefeed sample to room temperature and store in a dessicator untilused. To obtain an accurate measurement
32、of the mass ofsediments fed into the system, the sediment feeder shall beemptied and cleaned of material before each test. All particlesshall be fed into the system.8.3.2 After maintaining a constant flow rate through the testunit for a period equivalent to ten residence times of the testunit (see N
33、ote 3), the feeding of sediment shall begin at thetarget concentration. After all sediments have been fed into theC1746/C1746M 122influent pipe, flow shall be stopped after a minimum of tworesidence times of the test unit.NOTE 3Residence time of a test unit in a given test is equal to itsvolume divi
34、ded by the flow rate.8.3.3 The time is recorded for the sediment feed start, feedstop, end of flush, flow stop, and when draining or pumpingbegins. The test unit shall be drained by means of either a cleansump pump or a drain valve mounted 30 cm 12 in. above thefloor of the test unit. The first flus
35、h from this drain valve shallbe collected in a clean bucket to capture any sediment trappedin the bulkhead fitting. The rest of this drain water shall bediscarded.When water level in the sump of the test unit reaches30 cm 12 in. above the floor, draining or pumping shall besuspended.8.3.4 Lightly ri
36、nse all exposed surfaces into the sump. Allsediments captured by the test unit shall be moved into an areaof the sump away from the drain in such a manner as tominimize resuspension. After a settling time of at least 2 minfollowing sediment disturbance, draining or pumping shallthen continue in the
37、area cleared from sediments until water isapproximately 10 cm 4 in. above the floor. Slurry shall beemptied into a series of clean barrels. Add the contents of thebucket to the barrels rinsing lightly as needed to effectcomplete transfer.After each barrel is full, sediment is allowedto settle for a
38、minimum of 10 min then the water is carefullydecanted and discarded (see Note 4).NOTE 4Some variability in technique to collect residual sediment isallowable, though as much material should be collected as practicable tominimize error.8.3.5 All sediments and water remaining in the sump shallbe colle
39、cted using a wet/dry shop vacuum that has beencleaned thoroughly before its use. A clean filter shall be driedand weighed to a precision of 0.01 kg 0.02 lb and placed inthe shop vacuum before its use. This filter weight shall be usedin the determination of residual mass.8.3.6 The residual mixture of
40、 water and sediment shall beremoved from the shop vacuum and the barrels with a plasticscoop and placed in a clean preweighed non-ferrous tray. Aclean, fine-bristled brush may be used to sweep the surfaces ofthe vacuum and barrels to aid in collection. The collectedsediment shall be smoothed to a ma
41、ximum bed thickness of 2cm 0.787 in. without compaction. The shop vacuum filtershall be removed and placed in a separate clean preweighednon-ferrous tray. Trays shall be placed into a vented oven at nomore than 90C 194F, then the temperature raised to andheld at 110 6 5C 230 6 9F for at least 24 h u
42、ntil a constantweight is obtained when cooled to room temperature asdetermined by two successive measurements taken no less than2 h apart that show no more than a 0.1 % difference inmeasured mass when weighed to a precision of 0.01 kg 0.02lb. Weights obtained for all sediments (minus the tray and th
43、epretest filter weights) shall be added.9. Report9.1 Measurements for each datum shall be recorded for thefollowing parameters:9.1.1 Pipe diameter(s), orientation, slope(s);9.1.2 Specific gravity of feed material;9.1.3 Specific gravity of feed material;9.1.4 Temperature;9.1.5 Test Flow Rate;9.1.6 In
44、fluent concentration;9.1.7 Influent dry mass of feed material; and9.1.8 Recovered dry mass of feed material.9.2 Ascaled diagram including flow meter type and locationand sediment feeder type and location shall be included withreported results. All recorded times shall be reported.9.3 Unit removal ef
45、ficiency for the tested material at a givenflow rate shall be determined using:h(%) 5 MoMi! 3100 (3)where:h = removal efficiency,Mo= mass collected from sump of test unit, andMI= net mass added to the system (feedresiduals).10. Precision and Bias10.1 The precision and bias of this test method will b
46、eavailable within five years.11. Keywords11.1 discharge; filters; flow; hydraulic capacity; scour orresuspension; sediments; specific gravity; velocityASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Use
47、rs of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every
48、 five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technic
49、al committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or thro
