ASTM C1745/C1745M-24 PDF

Overview

ASTM C1745/C1745M-24 is the ASTM standard test method for the measurement of hydraulic characteristics of hydrodynamic stormwater separators and underground settling devices. This test method provides a detailed, reproducible procedure for evaluating the hydraulic behavior-such as flow, head loss, and velocity-of such stormwater treatment units under gravity flow conditions. The standard ensures accuracy in testing, facilitates the development of performance curves, and informs the technical selection and specification of devices used in stormwater management systems.

Hydrodynamic separators and underground settling devices play a critical role in stormwater treatment by separating sediments and pollutants from water before it is discharged. Understanding their hydraulic performance is essential to ensure they function effectively under varied real-world conditions.

Key Topics

• Hydraulic Characterization

  • Measurement of flow versus head relationships
  • Determination of head loss and loss coefficients
  • Analysis across a range of flows typical of system operation

• Device Testing

  • Only full-size, commercially available units may be tested (no scale models)
  • Testing may use alternate housing materials if core functional components match commercial specification

• Measurement Parameters

  • Flow, surface water elevation, and water temperature are measured to assess hydraulic performance
  • Precise calibration and setup are required for accuracy

• Test Method Procedural Integrity

  • Pipe diameters, lengths, slopes, and roughness values must mirror realistic installation parameters
  • Both manual and computerized data collection methods are referenced, with a strong preference for computerized data acquisition for continuous monitoring

• Reporting Requirements

  • Detailed reports to include diagrams of setup, measurement locations, and instrument types
  • Presentation of characteristic curves for system head loss versus flow rates

• Units of Measurement

  • Standard values are stated in both inch-pound and SI units; sediment concentrations in mg/L and particle size in mm or μm

Applications

• Stormwater Treatment Design

  • Hydraulic data supports engineers and municipalities in selecting and sizing hydrodynamic separators and underground settling devices for stormwater management
  • Performance curves developed under this method inform modeling and regulatory compliance

• Regulatory Compliance

  • Provides standardized data for authorities reviewing the capabilities of stormwater treatment devices for permitting or approval processes

• Manufacturing and Product Development

  • Enables manufacturers to validate and benchmark the hydraulic efficiency of new or existing designs under consistent testing conditions

• Operational Assurance

  • Facilities and operators can use the results to predict device behavior under a variety of realistic stormwater loading scenarios, thus supporting preventive maintenance and operational optimization

Related Standards

This test method references and aligns with several other established standards, including:

• ASTM D5242 – Open-Channel Flow Measurement of Water with Thin-Plate Weirs
• ASTM D5389 – Open-Channel Flow Measurement by Acoustic Velocity Meter Systems
• ASME MFC-3M – Measurement of Fluid Flow in Pipes Using Orifice, Nozzle, and Venturi
• Other withdrawn standards used for historical reference (e.g., ASTM D4409, D5640)

The approach in ASTM C1745/C1745M-24 is consistent with internationally recognized principles for the development of standards, supporting its applicability in global contexts.

By adhering to ASTM C1745/C1745M-24, stakeholders in stormwater management can ensure reliable, accurate measurement and reporting of hydraulic characteristics, enabling informed design, regulatory review, and product validation in environmental water treatment applications.