Figure 85. Existing Storm Drain
STORM DRAINAGE AND LOW IMPACT DESIGN Existing Conditions
There are currently three storm drain hard pipe connections from the campus to the city mains. There is a 39-inch reinforced concrete (RCP) connection to the 42-inch RCP City of Fullerton storm drain main along State College Boulevard, a 15-inch RCP connection to the 18-inch RCP City of Fullerton storm drain main adjacent to the State College Boulevard and Yorba Linda Boulevard intersection, and a 33-inch RCP connection to the 33-inch RCP City of Fullerton storm drain main adjacent to State College Boulevard and East Nutwood Avenue intersection. Storm water is also conveyed out of the campus through several curb outlets along State College Boulevard. As shown on Figure 85, all the private campus storm drain pipes are flowing under pressure and are flowing well over 100 percent full in an event of a two-year storm. There also many undersized pipes and inadequate pipe slopes. The athletic fields, the area north of the fine arts auditorium and the area west of the Pollack Library, are notable flood areas. It is stated in the 2010 CSUF Utility Master Plan by P2S Engineering, Inc. indicates that the City of Fullerton storm drain system is unable to handle the stormwater discharge from the campus as currently configured and sized. Moreover, the 2010 CSUF Utility Master Plan by P2S Engineering, Inc. Indicates that the City of Fullerton’s downstream receiving flood channels and infrastructure do not have capacity for additional flow from future campus improvements. Recent campus improvements such as the Student Housing Buildings west of the 57 Freeway are utilizing LID stormwater mitigation best
management practices (BMPs) that Alternatively, if bioretention basins treat stormwater discharge on site and and bioswales systems were used, reduce stormwater volume runoff. it would require multiple treating areas to accommodate the future developments, as shown on Figure 88. Proposed Storm Drain Furthermore, it has been determined Management that Clusters 3-4 and Areas 6-16, can either implement bioretention As mentioned in the section above, basins or a bioswales. Due to area all the campus storm drain lines are constraints, Cluster 2 and Areas 1-5 flowing under pressure in an event of only allow room for bioretention a two-year storm. Furthermore, the basins. The approximate required City of Fullerton is unable to handle additional discharge from the campus. bioretention basin and bioswale areas are summarized in Figure 86. Figure In order to alleviate this issue, on site 87 below show what typical deep/ post construction Low Impact Design shallow infiltration, capture and use, (LID) best management practices bioretention basins, and bioswales (BMPs) must be implemented. systems look like. A combination of Structural BMPs mitigate the impacts the above-mentioned allowable BMP of runoff and stormwater pollution methods can also be utilized. as close to the source as possible. Based on the Orange County LID Technical Guidance Documents, Recommendations BMPs are prioritized in order of design preference; the allowable BMP Due to the limitations of the campus methods (in order of priority) are: and City storm drain lines, it is 1.
Infiltration Systems
2.
Stormwater Capture and Use
3.
High Efficiency Biofiltration/ Bioretention Systems
recommended that any new proposed facilities implement LID BMPs that strive to produce zero stormwater runoff from at least a two-year storm event.
Deep and shallow infiltration systems were analyzed. From our understanding, deep infiltration seemed to be feasible for the following areas: A6 and A7. Shallow infiltration was analyzed in the other areas. Figure 86 shows the approximate deep and shallow infiltration system sizes. If infiltration is deemed infeasible, stormwater capture and use and bioretention/ bioswale systems should be explored. As shown on Figure 86, if a centralized capture and reuse system were to be utilized, it would approximately require 29 units of 10-foot diameter by 40-foot-long subterranean tanks.
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