Reso 1997-116 to 120 - Laserfiche WebLink

Home

Task 3 - Estimate Design Flows The design flow projections for the city of San Leandro's 1993 Sanitary Sewer System Capability Study and Master Plan will be reviewed. The Consultant will give considerable attention to flows tributary to each parallel sewer since they are critical to the location of proposed sewer alignments and crossings, the sizes and types of relief sewers, tie-in points and construction bypass schemes. Task 4 - Determine System Capacities The capacities of existing Davis Street corridor sewer system must be determined. This analysis will be conducted using hand and/or spreadsheet computations. The purpose of the analysis will be to route flows (developed by the City's Hydra model) through the Davis Street corridor to gain an understanding of hydraulic behavior of the system. Since several cross -connections exist between the parallel sewers within this corridor, potentially complex hydraulic conditions will be refined and simplified in order to determine the best repair and relief approaches. The Consultant will develop flow routing scenarios and assess the impacts of tie in and bypass schemes for north - south trunk and collector sewers. Task 5 - Evaluation of Alternatives The Consultant will explore alternative rehabilitation methods, siting, and relief scenarios associated with consolidation of Davis Street sewers and a new I-880 undercrossing. The alternatives will focus on rehabilitation of the existing 12-inch sewer on the north side of Davis Street between Orchard Avenue and I-880, and consolidation of the existing sewers in Davis Street that cross I-880, including the two lines that cross the freeway at an angle from northeast of Davis Street. Factors such as maintenance, available right of way, soil conditions, the potential for hazardous materials, traffic control, bypass pumping, dewatering, utility conflicts, and lateral reinstatement will be considered in cost and feasibility analyses. Open cut construction will be used as a basis for comparison, and the relative costs and benefits will be weighed against trenchless pipeline construction and rehabilitation methods such as sliplining, inversion lining, pipe bursting, boring and jacking, and microtunneling. Also, depending upon the availability and pertinence of flow monitoring data, additional dry -weather flow monitoring may be recommended. The Consultant will contact Caltrans to determine their requirements and concerns with respect to sewer construction in Davis Street and within and across the I-880 freeway interchange. It is anticipated that at least one meeting, attended by the Consultant and a City staff representative, will be held with Caltrans during the course of the study. Key to the design approach is the siting and method of crossing I-880. Potential boring and receiving pit locations, access routes, and manhole locations will be presented for consideration by City staff. The Consultant will conduct a workshop to present alternatives and recommendations to the City prior to the selection of a preferred alternative. Following the workshop, the Consultant will incorporate the City's comments and directions into the summary report. EXHIBIT A Page 2 of 4 AGRE\EXHIBITA.DOC (Word 6.0)