Laserfiche WebLink
<br />City of Elk River <br />Northeast Development Area Optimization Proposal <br />Page 4 of 8 <br /> <br /> <br />Sewer Design and/or Ten States Standards shall be used for planning <br />purposes to calculate sanitary sewer peak hourly flows. <br />d. Sewer Infrastructure Needs Assessment: <br />i. Utilize the newly created sanitary sewer model to estimate residual capacity <br />of the relevant portion of the City’s existing sewer trunk system. Residual <br />capacity will be identified for each trunk section. Provide recommendations <br />for upsizing existing trunk gravity sewer lines and/or existing sanitary sewer <br />lift stations, if needed, to accommodate projected flow. <br />ii. Provide preliminary trunk sanitary sewer sizing recommendations for the <br />growth areas based on the peak hourly flow estimates of the Elk River flow. <br />Diameter recommendations will be based on the proposed trunks flowing <br />85-percent full at the Ten States Standards’ recommended minimum slopes <br />for ultimate growth and peak hourly flow conditions. <br />iii. Determine if existing trunk sanitary sewer can be extended to serve the <br />growth areas by gravity. Gravity service will be given priority over <br />pressurized flow. Gravity service will be extended such that a minimum <br />cover depth of 10-feet and a maximum bury depth of 30-feet are <br />maintained. Bury depths beyond 30-feet will be studied on a case-by-case <br />basis if a greater bury depth can help avoid the need for a lift station. <br />iv. Recommendations will be provided for areas that cannot be served by <br />gravity in the form of sanitary sewer lift stations. If lift stations are needed, <br />provide recommendations for initial design firm pumping capacity, <br />ultimate design firm pumping capacity, recommended pump quantity <br />(initial and ultimate), recommended layout (wet well & valve vault, dry <br />pit/wet pit, etc.), forcemain diameter, quantity (single or dual forcemains), <br />forcemain material, and standby power recommendations. Forcemain <br />sizing recommendations will balance maintaining adequate velocities and <br />head losses per Ten States Standards’ recommendations. <br />v. A maximum of two (2) sanitary sewer alternatives/alignments will be <br />evaluated to serve the growth areas. One iteration per alternative is <br />anticipated upon initial City review. <br />vi. Develop one exhibit for each alternative showing proposed sewer <br />alignment to serve the planning areas and any recommended <br />improvements to the existing system. Alignments will be prepared using <br />ArcGIS Pro Software and will identify the following: recommended trunk <br />diameters, recommended sanitary sewer inverts for select inverts along the <br />trunk alignment, and recommended lift station locations with associated <br />forcemain alignment (if needed). <br />3. Water Distribution System Analysis: <br />Page 103 of 204