ASTM C1746/C1746M-19

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Designation: C1746/C1746M − 12 C1746/C1746M − 19
Standard Test Method for
Measurement of Suspended Sediment Removal Efficiency of
Hydrodynamic Stormwater Separators and Underground
Settling Devices
This standard is issued under the fixed designation C1746/C1746M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method concerns measurement of the efficiency of hydrodynamic separators and underground settling devices in
removing suspended sediment from simulated stormwater runoff under conditions defined herein. This test method is not intended
for use in determining field removal efficiency.
1.2 Units tested shall be of a size commonly manufactured, not a scale model. This test method is not intended to address
product scaling.
1.3 This test method is not for measuring the removal efficiency of filters or the scouring potential of hydrodynamic separators
and underground settling devices.
1.4 In this test method, only gravity flow operation is addressed—performance of units operating under pressurized conditions
is not addressed.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D422 Test Method for Particle-Size Analysis of Soils (Withdrawn 2016)
D854 Test Methods for Specific Gravity of Soil Solids by Water Pycnometer
D4959 Test Method for Determination of Water Content of Soil By Direct Heating
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 inlet (or outlet) rounding, n—radius of fillet at inside pipe junction with separator structure.
This test method is under the jurisdiction of ASTM Committee C27 on Precast Concrete Products and is the direct responsibility of Subcommittee C27.70 on Precast
Concrete Products for Stormwater Management.
Current edition approved June 15, 2012May 15, 2019. Published July 2012June 2019. Originally approved in 2012. Last previous edition approved in 2012 as
C1746/C1746M – 12. DOI: 10.1520/C1746_C1746M-12.10.1520/C1746_C1746M-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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C1746/C1746M − 19
4. Summary of Test Method
4.1 This test method describes procedures and equipment to measure the suspended sediment removal efficiency of
hydrodynamic separators and underground settling devices used for treating stormwater runoff.
5. Significance and Use
5.1 Each device has unique flow patterns and turbulence characteristics and may exhibit a wide range of efficiencies as
discharge, particle-size distribution, particle density, and flow viscosity (that is, water temperature) changes. The testing procedures
described in Section 8 provide a method of measuring the removal efficiency of these devices under a given flow condition, flow
viscosity (water temperature), and particle-size distribution and density. Therefore, the results of testing represent the flow,
viscosity, and particle-size distribution tested.
6. Apparatus
6.1 The experimental setup includes an influent straight pipe (without bends or fittings) of minimum length equivalent to ten
pipe diameters or 6 m [20 ft], whichever is less, upstream from the test unit and effluent pipe length equivalent to three pipe
diameters with a free-fall condition at its downstream end. Pipe shall have a Manning’s roughness coefficient not greater than
0.013.
6.2 The test unit shall be set up to reflect actual field installation parameters to the greatest degree possible, including inlet/outlet
roundings as supplied or recommended by the manufacturer.
6.3 Influent and effluent pipe diameters shall be the minimum size recommended by the manufacturer and shall be documented
in test results, as well as pipe orientation and pipe slopes (2 to 3 %). Pipe slopes shall not be negative.
6.4 The sediment injection point shall be at the crown of the influent pipe at a distance equal to 2 6 0.1 pipe diameters along
the centerline of the pipe upstream of the inlet to the treatment device to supply the sediments in the simulated stormwater runoff.
6.5 The sediment delivery system (feeder) shall be comprised of suitable means of sediment addition so as to provide consistent
sediment feed rate of solids (including an auger, vibratory hopper, well-mixed slurry injection system, or other).
6.6 A flow meter shall be installed to measure the water flow rate through the test unit.
6.7 All components of the experimental setup shall be inspected immediately before any testing to confirm that no damage or
obstruction is present and that there are no sediments or other deleterious materials therein. No leakage Leakage in system piping
or from the unit is allowed during the test.during the test is allowable as long as the leakage rate is less than 0.1 % of the measured
flow rate.
7. Sampling
7.1 Sampling of the sediment delivery system is intended to quantify the average influent concentration. Six feed rate samples
shall be taken from the feeder at of the injection point, at evenly spaced intervals over the total duration of the test. Each sample
shall be collected in a clean preweighed plastic 1-L [1.06-qt] clean, preweighed container over an interval timed to the nearest 1 s.
3 3
7.2 Feed rate samples shall be a minimum 100 cm [6.10 in ] or collection interval shall not exceed 1 min, whichever comes
first. Samples shall be dried, weighed to the nearest 1 g [0.002 lb] and recorded. The feed rate coefficient of variation (COV) shall
not exceed 0.10.
7.3 The influent concentration of each sample shall be computed from Eq 1:
W
sample
C 5 (1)
inf
Δ t Q g
M
sample
C 5 (1)
inf
Δ t Q
where:
C = influent concentration,
inf
W = dry weight of each sample,
sample
M = dry mass of each sample,
sample
Q = measured flow rate,
Δt = sampling duration,
Δt = sampling duration.
g = gravitational acceleration.
8. Procedure
8.1 Suspended Solids:
8.1.1 The specific gravity of the particles shall be assessed before the test using Test Method D854. The particle-size distribution
shall be determined according to Test Method D422 using standard sieves conforming to Specification E11.
C1746/C1746M − 19
8.1.2 For each test, a minimum of 10 kg [22 lb] of material shall be fed into the influent pipe. The suspended solids
-4 -3
concentration shall be within the range of 50 to 300 mg/L [8.35 × 10 to 2.50 × 10 lb/gal] as determined from feed rate sampling
in 7.1.
8.1.3 “Recirculated” water Water upstream of sediment injection that passes through the test
...