Gille-STPA 35 1Sewage on San Diego BeachesFor a casual reader of the San Diego Union-Tribune, the ongoing debate about sewageis incomprehensible. Scientists, congressional representatives, and regulatory bodies haveopinions about everything, and their opinions often appear to defy logic to the point ofbeing internally inconsistent.Former Congressman Brian Bilbray (who represented the district that includes La Jollauntil this year) presented himself as an environmentally-minded surfer. Indeed, Bilbray’sdisgust with environmental on the beaches where he used to work as a lifeguard has been amajor driver in his political career.A big source of beach pollution is sewage. Tijuana is estimated to generate 50 milliongallons of sewage a day; its main treatment plant handles 17 million gallons. An additional25 million gallons per day are treated by the International Wastewater Treatment Plant.The remainder flows from Tijuana across the border to IB and ultimately straight into thePacific Ocean. As mayor of IB, Bilbray was famed for having taken charge of a skip loaderto stop the flow of sewage.As a member of Congress, Bilbray carried out two contradictory actions. First in 1995 hesought a waiver of sewage treatment standards, so that San Diego could dump less seriouslytreated sewage into the ocean. Then he sought funding for the international sewage treatmentplant to help process Mexican waste. And finally, in 2000, he helped push through legislationto provide secondary treatment of the Tijuana sewage. As a result, sewage from Tijuanawill be held to a higher treatment standard than sewage from San Diego.Why would Bilbray seek a waiver to reduce sewage treatment but then push to insurethat all Tijuana sewage was treated? Regardless of your opinions of Bilbray and his politics,his handling of sewage runoff was relatively sensible in light of our scientific understanding.In your groups, select a group leader, spokesperson, recorder, and fact checker, makingsure that everyone has a different job than they had last time.Consider the following questions:(1a) Where do you expect sewage outfall to end up? (You may want to look at thetextbook’s discussion of upwelling and downwelling, and you may want to glance at thediscussions of waves and tidal currents.)(1b) Sewage planners spend a lot of time debating the length and depth of outfall pipes.The Point Loma pipe that handles San Diego sewage is about 4 miles long and 320 feet deep,while the Tijuana pipe is 3.6 miles long and 95 feet deep. What impact do you expect thepipe characteristics to have on where sewage ends up?(2) One big issue for understanding sewage treatment has to do with heavy metals.Tijuana is home to a number of maquiladoras that spew substances such as dioxin into theirwastewater stream. Contaminant concentrations are high enough to be toxic at the pipelinedischarge point. Why aren’t dioxin or heavy metal a problem when Tijuana sewage is mixedwith San Diego sewage in the Point Loma outflow pipe?(3) When plans were first made to address the heavy metals in Tijuana pollution,environmentalists advocated using a network of ponds to settle the toxic components ofthe sludge. IB residents were not so happy about the plan and suggested conventionalfactory-style sewage treatment instead. Why would neighbors feel so strongly about sewagetreatment ponds?Gille-STPA 35 2(3b) Who are the other stakeholders in the sewage treatment question and what opinionswould you expect them to voice?(4) Finally, given the risks of coastal contamination, speculate about the reasons whyenvironmentalists have agreed that the city of San Diego does not need to carry out secondarysewage treatment. What issues might be involved? Do you need additional information tohelp explain this apparent callousness toward the environment?Next time we’ll delve into the complexities of San Diego sewage, we’ll ask what processesare responsible for pollution and beach closures, and we’ll ask how sewage treatment mighthave to change as the population of this region continues to grow. Assign each group memberto represent a stakeholder, and divide up your outstanding questions so that everyone hassomething to research.For next time, read the remainder of this case, decide how the stakeholders that yourepresent might respond, and do additional background research on the outstanding questionsof this case. In our final meeting on this topic, your groups will be asked to present plans toaccommodate future population growth in San Diego County and Tijuana.· · · · · ·Despite all the media hype about sewage, sewage isn’t the only process responsible forclosing our beaches and polluting our oceans (nor does it receive all the hype). Read thefollowing OpEd piece by San Diego County Board of Supervisors member Greg Cox. Thisappeared in the October 18, 2000 edition of the San Diego Union-Tribune under the headline“Cleaning up our beaches and bays”.· · · · · ·No one wants to face the ugly truth about our most beautiful asset, but in San DiegoCounty there were 141 reported cases of contamination at area beaches last year. We hadunsafe water at our beaches more than 68 percent of the year. This means that a familywho wanted to go to the beach over a three-day weekend was likely to have been met withunsafe water for two of those three days.Beach closures in San Diego, typically caused by either sewage contamination or stormwater run-off, have become an all too familiar occurrence. Everyone has heard of sewagespills on certain San Diego beaches, but the reality is that our pollution problems encompassevery stretch of coast from the border to Camp Pendleton.The frequency of beach closures in our region has even gained the national spotlight. Inits July edition, Forbes magazine rated Mission Bay and La Jolla beaches among America’smost polluted. The magazine wrote, “If San Diego County has established itself as theCalifornia capital of sewage spills, then [Mission Bay] is its White House.” The same articlealso gave La Jolla Shores the “dubious distinction as one of California’s most polluted.”Sewage spills get more news coverage, but urban runoff is another major culprit in ourwater pollution problem. A growing urbanized area like San Diego County creates more andmore paved surfaces. Everything from rain and irrigation runoff, to soap suds from householdcar washing will run down the driveway, into gutters and is channeled through our stormdrain system,