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4550 NORTH 12TH STREET PHOENIX, ARIZONA 85014-4291 (602) 264-6831 FAX (602) 264-0928 GRAVITY SEWER FEASIBILITY ANALYSIS Babcock Lots 1-6 and Tremaine Park Neighborhood The Developer (Babcock) owns three lots (302-24-020C, 302-24- 034C, & 302-24-049C), generally fronting Arizona Avenue and adjacent to the existing Tremaine Park Neighborhood, near the cross streets of Arizona Avenue and Campbell Road in Chandler, Arizona. The developer has made several attempts over the last decade to develop these lots. The Arizona Avenue Sewer Extension project was constructed approximately 10- years ago with an as-built date of 10-21-16 and was required by the City of Chandler to serve as the off-site gravity sewer for the proposed Babcock development. Babcock is currently proposing to rezone and split the three lots into a total of six (6) lots. The purpose of this analysis is to reassess the extent and area of potential gravity sewer service connections to the Babcock 6-lot residential development and the Tremaine Park Neighborhood based on the Arizona Avenue Sewer Extension approved as-built plans and the current January 2025 City of Chandler Engineering & Design Standards Manual. The gravity sewer located at the termination manhole (MH) 5 (see sewer exhibit) serves as the downstream gravity outlet. Section 2.2.7.2 of City of Chandler Design Manual requires that sewer lines are installed with minimum of depth of 5-ft, additionally, section 2.2.10 requires that all sewer service taps are installed at a depth of 4.5-ft at the property line. MH rim elevations for this analysis were obtained from USGS, 1-foot contours. Manning’s equation was used to calculate the potential sewer extension. To meet City of Chander requirements for sewer depth, the maximum extension for the proposed gravity sewer running north out of existing MH 5 is 500 LF along Washington Street (see sewer exhibit and calculations attached). Extension of gravity sewer pipe past this limit would not be feasible because the sewer would be too shallow to meet Chandler’s minimum cover requirements. The Babcock 6-lots and four (4) additional lots have frontage along the potential gravity sewer extension shown in the sewer exhibit. The four (4) additional lots Assessor Parcel Numbers (APN) are: 302-24-021B 302-24-033A 302-24-035A 302-24-048H 6 / 2 / 2 0 2 6 4550 NORTH 12TH STREET PHOENIX, ARIZONA 85014-4291 (602) 264-6831 FAX (602) 264-0928 Review of the existing on-site plumbing piping for: alignment, elevation, and connection to the septic systems would be required to determine which, if any, of the four (4) existing Tremaine Park home sewer services have enough depth and slope to functionally connect to the gravity sewer and meet plumbing code. The following list of seventy-eight (78) properties in the Tremaine Park Neighborhood are not candidates to connect by gravity to the public sewer in the future because they are too low in elevation. Assessor’s Parcel Numbers: • 302-24-004D • 302-24-004E • 302-24-005A • 302-24-005B • 302-24-006A • 302-24-006B • 302-24-007B • 302-24-007D • 302-24-008A • 302-24-008B • 302-24-009E • 302-24-009F • 302-24-010A • 302-24-010B • 302-24-011B • 302-24-012F • 302-24-012G • 302-24-013A • 302-24-013B • 302-24-014A • 302-24-014B • 302-24-015B • 302-24-016 • 302-24-017A • 302-24-017B • 302-24-018B • 302-24-018C • 302-24-018D • 302-24-019C • 302-24-021A • 302-24-022A • 302-24-022B • 302-24-023A • 302-24-023B • 302-24-024C • 302-24-025A • 302-24-025B • 302-24-026A • 302-24-026B • 302-24-027C • 302-24-027E • 302-24-028A • 302-24-028B • 302-24-029A • 302-24-029B • 302-24-030B • 302-24-030C • 302-24-030D • 302-24-031 • 302-24-032F • 302-24-032G • 302-24-032H • 302-24-035A • 302-24-036A • 302-24-037A • 302-24-037B • 302-24-038C • 302-24-038D • 302-24-039A • 302-24-039B • 302-24-040A • 302-24-040B • 302-24-041A • 302-24-041B • 302-24-043G • 302-24-043H • 302-24-044B • 302-24-044J • 302-24-044K • 302-24-045C • 302-24-046G • 302-24-046H • 302-24-047G • 302-24-047H • 302-24-048G • 302-24-433 • 302-24-434 Conclusion: The existing gravity sewer can be extended a maximum of 500 linear feet north from the existing manhole (MH 5) while maintaining proper hydraulic performance. The six (6) Babcock lots fronting the gravity sewer have sufficient cover and can be designed with finished floor elevations that comply with plumbing code requirements. However, the majority (78) of the parcels within the Termaine Park Neighborhood are not viable candidates for future connection to this gravity sewer. Only four (4) additional parcels meet the depth of cover requirement for the public gravity sewer main located in Washington Street. Coordination with the City of Chandler determined that a standard 8-inch gravity sewer line would not achieve sufficient velocity under the anticipated low -flow conditions, so a 6-inch public line at a steeper slope has been proposed to achieve self- cleaning velocities. Additionally, due to the expected low sewer flows, the public sewer system will not be extended east along Campbell Road. N:\01\0260901\Enviro\Figures\2025\Chandler Sewer Figure.dwg Isiahv June 1, 2026 OF 1 1 BABCOCK LOTS 1-6 SEWER EXHIBIT 4550 North 12th Street Phoenix, Arizona 85014 Phone 602-264-6831 http://www.cvlci.com NOT TO SCALE EXHIBIT CO 1 MH A PVC 0.013 1,209 100 6 0.0100 5.00 1,203.98 0.00 1,202.98 362,592 2% 2.9 MH A EX MH 5 PVC 0.013 1,209 400 8 0.0052 5.35 1,202.98 0.02 1,200.90 563,106 0% 2.5 EX MH 5 EX MH 4 PVC 0.013 1,209 248 8 0.0036 7.45 1,200.88 1,199.99 467,881 3% 2.1 Estimated Ground Elevation (feet) Estimated Downstream Invert Elevation (feet) Pipe Diameter (inches) Sewer Line Capacity (gpd) % Full (Q/Qf) Velocity Flowing Full (fps) Upstream Pipe Cover (feet) Upstream Invert Elevation (feet) Drop Through Manhole/M eeting Crowns (feet) Pipe Length (feet) Babcock Gravity Sewer Calculations Upstream MH Downstream MH Pipe Material Manning's Coefficient Pipe Slope (ft/ft)