Houston's Effective Approach in Tracking and Preventing SSOs using Web-based Dynamic GIS and Power BI.

The City of Houston is the fourth largest city in the nation. Houston Water within the Houston Public Works department operates and maintains a large water and wastewater system. Its wastewater system includes approx. 39 treatment plants (WWTP) with a combined permitted capacity of 564 MGD, 5900 miles of sewer pipes, 127,000 manholes, and 385 lift stations spread out over 650 square miles to serve about 2.3 million customers. City of Houston's 311 Call Center receives an average of 1800 wastewater customer complaints per month. Issues may range from odor complaints, cave-ins to sewer backups in bathtubs. Houston Water is responsible for addressing these issues by mitigating the impact on public health and environment. Houston Water has a long history of using state-of-the-art technologies for managing its huge water and wastewater infrastructure. For Wastewater, it relies on systems such as; Infor IPS to manage work orders, service requests and tracking SSO records, HachWIMS to manage regulatory reporting, Infor EAM for facilities work order management and Enterprise GIS to support asset management for collection system. Recently, Houston Water introduced ArcGIS Online and Business Intelligence Tool, Power BI in every aspect of full-cycle process- starting from receiving customers call to satisfactory resolution of the problems.

THE PROCESS
Initial Call It all starts when a possible SSO is reported to the City of Houston's 311 Call Center. The 311 operator generates a service request (SR) which is logged into the Infor IPS. Once a service request is initiated, the clock starts ticking for the first responders, wastewater inspections team to respond to the request. Depending on the type of request -- a priority level is assigned to each Service Request. As an example- 'High Priority' is assigned to an active SSO that is threatening to enter a storm drain. A 'Medium-Priority' may be assigned to an odor complaint. First Responders Wastewater inspectors are equipped with a tablet to notify them of newly created SR through Infor IPS dashboard and also to enter field data into the Infor system. Inspectors are responsible to identify the type of SSO- Public or Private, where it occurred, the volume, flow rate, status of manholes upstream and downstream of the incident location and the possible cause. Inspectors create an SSO incident in the Infor platform for the stoppage team to take further action. The start times and flow rate data are recorded in real-time and cannot be edited to maintain the integrity of data. Stoppage team- Further Investigation Stoppage team are equipped with jetting and vacuum trucks to clear a blockage, stop the SSO, clean and disinfect the area and report the confirmed cause of the SSO. Stoppage crew is also equipped with tablets to enter details of SSO such as confirmed cause, actions taken to mitigate the SSO, and request for work orders. Depending on the needs work order could be issued for televising the line or installing bypass pumps. Quality Checking the Data for Regulatory Purposes Data is validated and confirmed in a weekly SSO meeting before weekly reports are sent to State Regulatory Agency- TCEQ. The meeting is attended by various stakeholders that includes regulatory team, inspection and stoppage team, customer service and Houston Health Department (HHD). ArcGIS Online and Power BI Dashboards provide the real-time and historical reference information. Recurrence Prevention through Analysis Greater than 70% of all public SSOs are preventable SSOs as they are caused by the accumulation of grease and rags/non flushable wipes in the sewer pipelines. Repeat SSOs are plotted on a dynamic ArcGIS map to identify SSO hot spots. This makes it easier for the wastewater analysis group to target high priority areas for Preventive Maintenance (PM) cleaning. A sample hotspot snapshot is shown in Exhibit 1, which illustrates the effectiveness of the PM cleaning program by reducing the preventable SSOs from 63 SSOs in 2018 to 29 SSOs in 2019.

Tracking Wet Weather SSOs
SSOs are also caused due to hydraulic capacity constraints in the collection system. Power BI is used to track the high volume (over 100,000 gallons) and number of repeat SSOs (3 or more) occurred during wet weather in previous three years in one manhole, as shown in Exhibit 2. This information is used to develop a capacity remedial measures plan. Fats, Oil and Grease (FOG) Program Houston Water's FOG outreach group uses ArcGIS Online based tool for targeted campaigns. HHD administers FOG Generator Interceptor Inspection program. HHD maintains a database for the Grease Trap inspections that are used by the FOG Outreach group to identify target areas that includes apartment complex and Food Service Establishments. Both, HHD and FOG outreach group use similar density maps as seen in Exhibit 1 for their respective needs. Intelligent Manhole Covers Houston Water uses intelligent manhole covers to provide real-time water levels to pro-actively detect a potential SSO that helps to mobilize maintenance crews to prevent SSOs from occurring. The continuously monitored manhole covers provide information to determine the rate of accumulation of debris in the pipes that eventually helps to develop PM cleaning program. The data from the manhole covers along with the lift station SCADA data are also used for verification of the collection system hydraulic models. Business Intelligence software such as Power BI and ArcGIS Online Dynamic mapping tools are used to efficiently process, visualize, analyze and share the outcome to present in a meaning way to effectively use the resources. The experience and effectiveness of using these emerging techniques and technologies, some of which are free, would be beneficial for water and wastewater utilities of all sizes.