Design and Implementation of a Sluice Gate–Weir Device for Flow Measurement in a Sewer Collector

3D EAU designed a bespoke flow measurement solution for a French water utility, achieving measurement uncertainties below 10% in a complex wastewater collector to ensure highly accurate quantification of volumes transferred to Switzerland for treatment.

CLIENT REGIE DES EAUX GESSIENNES (FRANCE)

STRUCTURE 2.5 m diameter wastewater collector

OBJECTIVE High-accuracy flow measurement

PERFORMANCE Measurement uncertainty below 10%

THE PROJECT

Metering cross-border wastewater flows with a custom-built device

Improving the reliability of flow measurements is now a major challenge for wastewater network operators. Where hydraulic and structural constraints make conventional solutions difficult to implement, devices specifically adapted to each structure must be developed.

3D EAU was commissioned by the REGIE DES EAUX GESSIENNES to develop a solution for metering the volumes flowing through a 2.5 m diameter collector fitted with a dry-weather channel.

A strategic point
Wastewater is transferred from here to Switzerland for treatment.
A billing reference
In the long term, this measurement will serve as the basis for invoicing the volumes treated.
A high level of accuracy
Required to make the measurement reliable enough for invoicing.

THE HYDRAULIC CHALLENGE

Why was a bespoke device needed?

Given the complex geometry of the collector and the high flow measurement accuracy required by the authority (uncertainty < 10%), 3D EAU designed a sluice gate–weir device capable of accurately measuring flow in both dry weather (flow passing under the gate) and wet weather (flow passing under the gate and over the rounded V-notch weir).

OUR APPROACH

From field survey to bespoke measurement design

Site survey

On-site inspection and geometric survey to capture the site's physical layout, existing structures and key hydraulic features.

Hydraulic assessment

Detailed analysis of hydraulic behaviour, site constraints and operational challenges to understand the specific measurement requirements and project objectives.

Tailored measurement solutions

Development and comparison of measurement concepts suited to the site's hydraulic conditions, practical constraints and measurement objectives.

Custom design and sizing

Detailed sizing and engineering of the selected solution to ensure reliable measurements, hydraulic performance and seamless integration with the existing site.

THE RESULTS

Overseeing the project from design to commissioning

Once the design was validated by the Régie des Eaux Gessiennes, 3D EAU oversaw every step of the project until the instrumentation was up and running:

01

Fabrication drawings

Production of the fabrication drawings for all stainless steel components of the device (rounded V-notch weir, gate, structural reinforcements, etc.).
02

On-site installation

Installation of the measurement device, in coordination with the instrumentation (probe supplied and installed by SEMERU).
03

LiDAR survey

Geometric survey of the site, equipped with the device, using a LiDAR scanner.
04

3D CFD rating curves

Refinement of the stage–discharge rating curves for the installed device through 3D CFD modelling, resulting in low measurement uncertainties (< 10%).