Description

This application allows City of Salinas staff to estimate the size of sanitary sewer spills that resulted from breaks in gravity mains. City staff select the location of the break, using the system network as reference, input the start and end times of the spill, and receive a volumetric estimation of gallons spilled and number of homes upstream of the break. In additional to other estimation methods, staff are able meet rapid reporting requirements with a repeatable and data-backed tool. This approach also saves employee time during a time sensitive period and reduces reliance on error-prone manual calculations and paper map interpretations.

The Geoprocessing Service takes the users inputs, snaps the inputted point to the nearest manhole or network node, then conducts an Upstream Trace on the City’s sanitary sewer Geometric Network, which contains pseudo connections to residential parcels. These connections were GIS generated based on proximity to nearest gravity main to establish most likely lateral connection points. These connections are used to select features within another non-network dataset containing all residential housing addresses per parcel. Next, inputted time information and the count of total affected addresses are passed through an algorithm that uses average flow rates following a diurnal pattern. Finally, the estimated sewage spill volume, total number of affected residences, and a GIS layer of affected residences are returned to the user within the web application.

I first developed the application as an ArcMap Geoprocessing Script using ArcPy to conduct an Upstream Trace on a sanitary sewer Geometric Network, the script was then hosted on ArcGIS for Server as a Geoprocessing Service and accessed in an ArcGIS Online Application using the Geoprocessing Service widget. While the script functioned well in ArcMap, getting it to work as expected in ArcGIS Server/Online took the bulk of the development time, as many errors and bugs had to be resolved.