## 2 Materials and Methods
### Monitoring  
A programme of monitoring was designed to capture any changes in runoff in the drainage system around the interventions at the street level. Flow monitoring solutions were installed at multiple locations within the study area's sewer network, and a telemetered user interface (UI) was developed for the local community centre to enable near real time display of data, with the aim of engaging the local community on the changes that SuDS could deliver.  
Establishing the monitoring was not straight forward since the project was undertaken in a real-life setting. A series of consultations with the project team and stakeholders was undertaken to determine the type of monitoring equipment to be used, and the location in which these devices would be placed. Sensors installed in drainage networks must be able to provide continuous recording of data, remote data transmission and be resistant to water and chemicals [37]. Water level measuring devices are most commonly used for these applications [37]. Several options were considered, including v-notch inserts and pressure sensors, area velocity flow meters and ultrasonic level-to-flow meters. Five manholes were identified as priorities in which to install monitoring devices, and a secondary set were identified as potential alternatives. A survey was undertaken of the utility's and local authority's manholes in the study area. An inspection of the proposed locations identified a number of constraints. Some of the proposed locations were not suitable for monitoring in terms of access, space and condition. For example, some of the sewers did not have inspection chambers present, the flow did not always accurately map onto the plan and some of the manhole covers could not be lifted, as they were seized.  
Following this initial investigation, seven manholes were surveyed by the civil engineering contractor and engineers from the monitoring team (Figure 6). Three of the manholes (2, 3 and 5) were deemed unsuitable, due to high level inflows and/or inaccessible manhole covers. The remaining four manholes (1, 4, 6 and 7) were evaluated for sensor installation. However, manhole 4 was later removed from consideration due to an unusual high inflow. The three manholes chosen for the study (1, 6 and 7) were located next to SuDS interventions; manhole 1 was downstream of street level raingardens on Pine Street, manhole 6 was upstream of the proposed SuDS tree pit locations on Poplar Street, and manhole 7 was downstream of the proposed tree pits on Poplar Street. All three manholes had suitable chambers to accommodate monitoring equipment on evaluation.  
An ultrasonic sensor and bracket were drilled and installed on to the upper wall of each of the three manhole chambers. Each mount point was chosen to provide the most accurate level data achievable in the chambers. A remote terminal unit (RTU) was installed in each of the chambers, although it was acknowledged that this may need to be later surface mounted, due to signal strength. Following this, the micro-PC was configured and installed in the local community centre, connecting to an active internet connection within the building. Finally, the user interface (UI) was configured and programmed to provide a dashboard showing level, calculated flow, system conditions and rainfall information, collected via a rain gauge installed on the roof of the community centre. Level data was recorded by the ultrasonic sensor in each manhole at 5 min intervals, providing up to 288 individual data points per manhole per day.