Jacobs Engineering Group Inc 9/6/2019 Amendment 1

Subtask 7.3 SEI to SRI Intertie Alternatives Analysis Subtask 7.3 will consist of an Alternatives Analysis (Analysis)for three different design alternatives: Alternatives A, B, and C.These three alternatives correspond to three possible configurations of a 30" diameter intertie connection from the SEI to the SRI at 36th St. Alternatives A and B include penetrations into the existing SRO8 structure,while Alternative C is a new tap onto the existing 72" diameter pipe to the north of SRO8 with a concrete encasement and access maintenance hole or other appropriate structure and pipe connection method.There is an existing 30" blind flange stub from the SEI that can be connected to the other end of the intertie, and which will be evaluated during this Analysis. This Analysis includes the evaluation of the intertie as well as the connection to the vault (or existing pipe). It is understood that the system may be shut down during dry weather for several days for the construction of the selected Alternative. The Analysis will consider feasibility, risks, and costs for each alternative. Once the Analysis is complete, an in-person workshop (Conclusions Workshop)will be held to discuss the conclusions and recommendations of the Analysis. A subsequent technical memorandum (Conclusions TM) will be developed to document these Subtask 7.3 activities. (It should be noted that the Conclusions Workshop and Conclusions TM will include a summary of the activities from both Subtasks 7.3 and 7.4.) Specific Alternatives Analysis activities include: • Document Review:The Service Provider will review plans, reports, as-built drawings, and other documents related to the existing SRO8 facility,SEI and SRI pipelines. Review of these documents will guide the Analysis. Specifically, as-built drawings will be reviewed to determine the placement of existing reinforcing steel. Additionally,the Service Provider will review the previous geotechnical reports and map showing the locations of various boreholes in the vicinity of the project. It is understood that there may be some landfill gas vents in the project area which should be considered in order to minimize impacts to the vents. • Structural Analysis:The Service Provider will conduct a desk-top study structural analysis of the SR08 vault wall for penetration from Alternatives A and B.This analysis will incorporate an assessment of the vault walls to confirm the strength of the wall to prevent cracking from the penetration,or options for stabilizing the structure if required to allow for the pipe penetration.The design will include modifications to the SR08 vault due to any penetrations. Other items that will be considered in this analysis include the internal pressure from surcharging which could impose critical loading conditions. The Service Provider will make a recommendation on the maximum diameter penetration that should be attempted in order to maximize flow capacity of the intertie. • Flow Analysis:The Service Provider will review the modeling effort contained in the City's existing Comprehensive Sewer Plan to understand the current flow system in order to develop the pre-design drawings. (A more detailed flow analysis may need to be conducted during the detailed design phase of the project.)The Service Provider will coordinate with the City to determine and document several items related to hydraulics.This flow analysis assumes only 1-dimensional flow calculations will be conducted to determine feasibility of these designs.These items include: o Range of pressures anticipated in the SEI and SRI interceptors o Anticipated maximum flow rate in the 30" intertie o Anticipated maximum velocity in the 30" intertie o Method of flow control in the 30" intertie • Permit Requirement Analysis: For each Alternative,the Service Provider will prepare a permit matrix that identifies the permits for each Alternative. (During Phase 2, Design and Bid Services, services will be provided to assist the City in obtaining the required permits identifies for the selected Alternative.) • Development of Pre-design Drawings:A total of up to three (3) pre-design drawings for each Alternative will be developed (totaling a maximum of up to nine (9) drawings).These drawings will be developed for use during the Alternatives Analysis Conclusions Workshop and will be incorporated into the TM.The pre-design drawings will be to scale, however informal.They will be developed to a level 61P A G