| Description | BES Asset System Management “Pipes Surcharged to Ground Surface” layers (2-, 5- and 25-year), description and disclaimer August 4, 2015 ABSTRACT: This layer provides predictions of assets undergoing surcharged pipe conditions for the Combined Sewer system of the City of Portland Bureau of Environmental Services (BES). These are derived from modeling results using the BES Explicit modeling system (EMGAATS). Surcharging occurs when the hydraulic capacity of a pipe is exceeded by inflows generated from a given rainfall amount for the 2-, 5-, and 25-year return period. Under these conditions, a certain volume of water will attempt to leave the sewer pipe, either up manholes, service connections (laterals), or other hydraulic structures connected to the sewer pipe. These layers represent surcharging that is predicted to rise up to the ground surface at either the upstream or downstream end of pipes as simulated with the BES model. USE CONSTRAINTS: This data is to be used by City of Portland BES/BOM staff or BES modeling contractors only. Appropriate uses currently include initial or planning level estimates of pipe capacity and surcharging conditions in the combined sewer area only. As this data is not updated on any regular basis, use for maintenance and construction activities should be limited to reconnaissance level use, particularly where pipe access or long-term sewer bypass pumping issues during likely storm periods are being considered. Under these conditions, please refer back to the Asset Systems Management Division for confirmation/reassessment of surcharge conditions in your specific area and for your desired time period. CURRENT STATUS: Work in progress. DISCLAIMER: Surcharge data not field verified and subject to change at any time. UPDATE FREQUENCY: Irregular and infrequent CONTACT: Arnel Mandilag (x3-7256) Ning Mao (x3-7857) DATA SOURCE: BES Asset Systems Management - Modeling results from the BES Combined System Plan and Basin Model Updates. See Model_YR field for year that model was run and results were extracted |