preter: : =e ete raat" Pega cata eie ota ene > abe ee RN tee ears eae at epaghtnd eee ee Grade 5 O2?TEOO TOED O MOO IOHM/18lN ob inns v in RN) i \) ‘ + es ‘ ; STUDIES ON COLIFORM BACTERIA DISCHARGED FROM THE HYPERION OUTFALL FINAL BACTERIOLOGICAL REPORT by Sydney C. Rittenberg A Final Report Submitted to the Hyperion Engineers, Inc. by the University of Southern California August 29, 1956 Ae ary at TABLE OF CONTENTS \ PAGE INTRODUCTION @eooerereeeeoevoosvoeve Geet eee eeooeveeeeeeoeeeeeoee eee COLIFORM BACTERIA IN THE WATER Radioactive Tracer Study .... @eeeoeonvetmpeoeaeeeeeoevseeoeeoeeeeeeaeeeoeee @eeeoeoeneeegevee eee eeeoeeaeoee ese ea ee ee © Dye Patch Experiments @eenpneaoeaeooesoseseseeeeeeeoevse eee eeeeeee2e@ Subsurface Distribution of Coliforms .....cccccccccccccece Bumeau Of Saniutats On RES tS) 4 svcte.eieletevelcle cle lolaleioie siele tele eye cle Summary of Water Data @eoeenoveeseevesoneeeeeeeeeeeeoeoeeSeeoeeeo eee CONCLUSIONS WITH RESPECT TO STATE STANDARDS ....cccccccseccce COLIFORMS IN THE BOTTOM SEDIMENTS @@eeesoseoecoveoeeeeeeeoeeseeeeeeene @ Introduction e@oeee*eveeoneveeoneeeeeeaeenveene eG eagseeveeeeeeexe eo 8 &@ & Sampling Methods @eoeeoseeveveeveaeeeaoeoeeveeeoeeveeeeeHaeeoeevee e288 @ © Results e@eoeoeeneneeaoea GSeoeeoe ees ee eeeeoeoeeoese eae Fee eer eer ee eee eo oe & Discussion eeoooaoeseoeecve soe oo evs eeeeeeen O©Ooe @eeeeeeoeoe see eoeeeeee @ Summary e@eeeescoceoceeoconoeeeeeeeesesewvaeeeeceoevsee eeeeeseeeeaeoeseeeoaseeoeeee APPENDIX May 1 Report 1 2 2 iy rayne eeerenene eee ba wien pba My i a ee vin : wih et Q) Mm Ol .00I 0 4 8 l2 16 20 24 TRIMS UN Te OouwiRsS 28 ay Aan Sih ' DEE iN ni ny Ae rai iit Wath Hi at Di) includes data from four types of measurements. The closed circles represent the minimum dilutions (maximum radioactivity and there- fore maximum effluent concentration) detected on the various underway traverses, and the upper line is the approximate best fit through these points. The squares represent the dilutions calculated from the radioactivity of the samples collected in the two dye patches, and the lower line is the approximate best fit line through these points. The triangles and open circles are dilutions calculated from radioactivity measurements on the surface samples collected underway and from the surface samples collected at the profile stations, respectively. The main point to be emphasized, besides the marked dilution of the radioactivity with time shown by all four types of measure- ments, is that there is no great Hatt erenre between the minimum dilution found by traversing the sewage field and that measured by following a dye patch. The dilution curves from the two types of measurements do diverge somewhat; however, the difference between the two lines at six hours (the usual length of most dye patch experiments) is only about two fold. Considering the variations that occur in the properties of the effluent being discharged, this difference would not introduce any significant error in measurements of coliform disappearance rates. It can be concluded that the dye patches represent a typical part of the sewage field and that confidence can be placed in data obtained by the dye patch technique. panes ane tat met taney viae: oe @ poise dame tte say we detrtoqorg ‘ont ink ‘ara. tay | tnas Hiagee ene soubonnia Foo etatow besncinblers tate | nad th 9d Won : te txa4 ‘see a Dilution Calculated from Radioactivity and Observed MPN's of Coliforms A total of three samples were taken in the boil during peak radioactivity and these were analyzed for the MPN's of coliforms, radioactivity, and chlorinity. From these data one can calculate the original coliform density of the undiluted primary effluent. The data from these calculations are presented in Table I. The values obtained are reasonable for a primary treatment effluent, although the geometric mean of 720,000/m1 is probably higher than would occur if a larger number of determinations were involved (see page 29). From the calculated MPN of the undiluted effluent, one can calculate the expected MPN for any dilution of the effluent as measured by radioactivity. The results of such calculations are shown in Figure 2. The three lines are based on the maximum count, the geometric mean of the count, and the minimum count of Table I, respectively. On the same graph are included the observed MPN's of all the surface samples analyzed for coliforms plotted against dilution calculated from the observed radio- activity of the respective sample. It can be observed that beyond a dilution of 1/100, the majority of the samples gave a MPN well below the minimum calculated range. These data show that factors other than dilution are operating to reduce the coliform population within a relatively short time after the effluent leaves the outfall. A similar conclusion was previously reached from calculations based on chlorinity (May 1 report), where an even greater difference between observed and calculated MPN's existed. The significance of the greater difference is discussed later. “nanothtne oh to tm oe ia ay ad Fe ry Tait Ke ir i ” i “tance sumtain 9A bee staves sit ‘to mun sknsanoes at 12903 ont ‘bob load ous santa ome ont 10° ytovitosqaes. ie sa me ‘emetites no ese Fane sil anal seg trae sult fly to a ~okbar, aire wat wort tetatentas aokautin tenkaga | badtos ‘art awapesto od AD | cs piqnss ovkdosqaes oat 2 * even i ot, je ‘ypineten oad ot gaa Retalvata> akan ont woLae ter Wt f a8 = 0! ‘pat soubor ot avian ome aottn tee aes acto Les anda sat 000‘*07zz 0000S 000‘ 08r 000‘OvE 000‘ose‘T 000‘026 000‘sss 000‘ 00€ AZ TATPOVOTpeI pA FurroTyo WOT pezeETNoOTed zUENTJJS peyntTtpun fo Ndw °00/0 09°8T JO Bare dy} UT T3azeM Bas paeynTTpun jo Az tutTzIOTYyO Teurou e pue 00/0 97°0 JO eBemas ayz jo A}TUTIOTYS TeuTSTIO ue soumssy “T 000‘ Tz 9€/T 92/T 000‘ €T Se/T LT/T 000° vs Sv/T €2/T 000‘ €T AYTATLOCOT PET Ay putsoryo punoj Tw/NdW WOT UOTINTIp pe,eTNoTeD SWUIO JT TOD quent[jJjq AreutIg pent pun ay} JO SWIOJTTOD JO S,NdW PE}BTHOTED I WIadVvL UBdSU DTI} SOWIOdSH VWIe wotze4S c# yozed ohq T# yozed ahq atdues Figure 2, Calculated MPN for various effluent dilutions aS measured by radioactivity. SEIN Me = TW / NIN O===9) MAXIMUM CALCULATED fe) © © MAXIMUM CALCULATED Xx x Dye patch samples 0 Surface— vertical profile samples 4 S © Underway surface samples 107 lo? MIO IKeIN} 10* fal 17 ae ute | waa JAD) MUMIX: ta A Ii BATA I eA MAT Ti 3 enc ’ Winlienuy ar lqmse ateg yl ® an Disappearance of Coliforms with Time The MPN's of coliforms for all surface samples are plotted against time in Figure 3. The straight line is an approximate best fit line drawn through the geometric means of the data grouped somewhat arbitrarily as shown on the graph. The line joining the geometric means of the data collected on the same day by the Bureau of Sanitation, Los Angeles, is also shown on the graph. These data provide the best estimates of the rate of coliform disappearance on the day of the tracer experiment. It is obvious that there is no significant difference between our data and that obtained by the Bureau of Sanitation. The average rate of decrease of MPN is of the order of one magnitude (90%) every 4 to 43 hours and the average count reduces to below ten in about 15 hours. On the day of the trip, the sewage field instead of con- sistently moving away from the outfall doubled back on itself while showing a net movement towards the beach (see NSE report). It is possible under these circumstances that the coliform population of the tagged effluent was reinforced by contributions from younger effluent, and this could account in part for the terminal decrease in disappearance rate shown by the Bureau of Sanitation data, and the three relatively high MPN's obtained by us between 13 and 16 hours. and Radioactivity The data in Table I show that a significantly greater dilution of the effluent is found when one calculates this value from radioactivity measurements as compared to values calculated dake er eke nk ad eos ho: S Mienk prsat paswoe Bey babeae aut #6, yal oat me | Maa?E a0 Wood beidvob, Chattny of? aot) Yams aniven une an Mabe. aw e2n) Hon 9d ait ataavo? saxon rom Heit f gokwods othe | mrp Yhlao et tnd seonatenvorts sordt ashe oidtaeag ek 98, “pool todhxtaey ‘ee biasotnten any Hise ENG: borgat art to: mob gatveoq ‘ail to dks eh) Pknde ait) bea saint te RON aa ed eee, oie ee awit, pen nada sqqonts med maori, tuetast Vascaeambeny Sisk os wouuiaatae cidiimnil tsi! sin vata Seikfata | ores idseos Mage Bi Say Fish | t ; beter ohne enna staal, amu ind ‘bane ee 10 Figure 3. The MPN's of coliforms for all surface samples versus time during radioactive cruise. ae 6 ‘ ie te ier ove fon Io a) Win Dye patch Vertical profiles Underway Bureau Sanitation—geom. mean Geometric mean of all Hancock data arbitrarily grouped as shown 0 2 4h 6 8 10 l2 l4 16 18 7 rey Hat ‘ Barn Same 11 from chlorinity. The differences between the calculated dilutions become even greater as the effluent moves away from the boil. Using the MPN‘'s determined for the boil samples and effluent dilutions calculated from the two types of measurements, one can calculate the MPN‘'s for the undiluted effluent (0"* sample), and for the dye patch samples taken after zero time. These data, along with the observed MPN‘'s are plotted in Figure 4 using the geometric mean of the results from the two dye patches in all cases. Since essentially no radioactivity existed in the area of the outfall previous to the one hour introduction of the radio- isotope tag (actually the background count was determined and corrected for), the decrease in radioactivity is a measure of the total dilution of this one hour's volume of effluent. If this effluent were being introduced into undiluted sea water, then the dilutions measured by radioactivity and chlorinity would be the same. However, as is seen from Figure 4, dilutions measured from chlorinity are much less, which must mean that the tagged effluent was being diluted mainly with the untagged effluent in the area. At eight hours, for example, the tagged effluent at its maximum concentration constituted only 1/16 of the total effluent in the sample. If the effluent field moved away from the outfall at all times, then dilution of the tagged effluent on its outer boundary would have to be with effluent of older origin and therefore lower coliform density. As previously mentioned, on the day of the experiment the tagged field curved back towards the outfall and there could have been some dilution of this field with ee pie oi, bs ™ ; a yy ye _ i a : oe ae y . : y : LA, Fy ne 8 | sf ay ye >i fd Pier y eo 4 PEO RA OPTS Shaw RAY a Pot im ee, A. are N bd 7 isis alias Ly 207 smoH Aap ep iy Figure 4, Calculated MPN's/m1 from chlorinity and radioactivity versus time from outfall. 12 betsiuolsd i owties G kv. i ay ne 10> 10° NS 2 TIME CALCULATED FROM CHLORINITY =e \\ CALCULATED FROM \ RADIOACTIVITY OBSERVED 4 6 8 l0 IN HOURS 13 younger effluent. Unfortunately, the data do not permit an estimate of how much younger effluent could have been present in the samples analyzed. In a steady state condition, with constant discharge of unchlorinated effluent instead of only two hours discharge sub- sequent to the introduction of the tag as was the situation, the coliform counts could have been higher than those observed and thus a slower disappearance rate would have been measured. Since the coliform count on the beach depends on the disappearance rate and the time of travel to the beach, a slower disappearance rate with a longer time of travel would have the same effect on the beach count as a more rapid rate of disappearance with a shorter time of travel. The problem of the reinforcement of the coliform population of a particular volume of effluent by younger effluent can be examined in another way. Let us assume that a volume of effluent "Aw. discharged six hours before a second volume "B", has a path of travel that causes it to intersect volume "B” when the latter is two hours from the outfail. The danger of pollution on the beach would, of course, be from volume “B"™ and not from volume "A" in this situation. The total time of travel of "A" to 'B™ is 8 hours, and during this period the coliform population would be reduced by about 90% from dilution alone (Fig. 1). Volume "B", having traveled only two hours, has its coliform population reduced about 20% due to dilution alone. The contribution of coliforms from "Bt to “At is significant, but the contribution of coliforms from *A*®" to *"B* is not, and calculated numbers of coliforms reaching the beach from “B™ based on normal disappearance Ain) i pa kiates oq i907 it hina ait? ¥e Hismyd7O% i ad Reo: tneg this: Yonraray vd tasuLt?s , | amntey snat m0 ae : he tad Pied: peer pe) boos Be soled etuoe ) ; Mar. 14 os eon tak oy i | edd; mo ns 7 bd Z Me ae ai ab a # sige ‘ Lo Wc | _ veto. Goat Meme bis me suid Cov wir ; a ; “AOD te po ce bilvow wo kis z Wyo wee REL GS 4 e: ca [ROR 14 rates would not differ appreciably from the actual numbers. The extra disappearance of coliforms due to factors other than dilution is clearly seen from Figure 4. The data are strikingly similar to those obtained in the vicinity of the Orange County outfall (May 1 report, Fig. 4), except that in the latter area the calculated MPN‘'s based on chlorinity show a slow but significant decrease with time that is not seen in the Hyperion data. The probable reason for this is that the effluent field around the Orange County outfall covers a smaller area and in most of the experiments performed the dye patches moved fairly consistently towards the perimeter of the field. Subsurface Radioactivity Measurements The subsurface radioactivity measurements taken at the profile stations indicate that mixing of the discharged effluent, most of which reaches the surface, eventually distributed it throughout the entire column of water in the part of the bay sampled. A qualitative inspection of the chlorinity data show that most of the subsurface water below 15-30 feet in the vicinity of the outfall is of essentially normal chlorinity, whereas the surface water for a considerable distance around the outfall contains well over 1% of the fresh water effluent (see Final Oceanographic Report). This means that all of the water in the bay is not equally effective in the dilution of the sewage and that surface currents and surface (horizontal) diffusion and mixing play the most important roles in effluent disappearance. t 7 Ds th Petobiszaie ‘tae teen t ataiandhe ant vidiboes tokaw Xe oom . 0 eile Yo die outs inh Se io wy ‘gh Hayne wat svodguoy rnent i ae ul pat kn bie sade anand at ‘ agi ithoa tana tardy yor * { % mak t tk hy Hoh) a eR D0 Si, eS fea jon at $60 malt mk sath ee bos) . sa hatl ah ain eostwoe kinds ey semi? 15 Using the radioactivity, chlorinity, and MPN data from the subsurface samples taken at the profile stations, one can cal- culate dilutions and expected MPN"s as was done with the surface data. For these calculations, all subsurface samples were grouped together independent of depth or location and geometric means were calculated. For any comparisons made, only samples that were determinate for both parameters being compared were used. Thus, out of a total of 21 subsurface samples examined, ten were indeterminate for dilutions calculated either from radioactivity or chlorinity and only eleven could be used for determining the geometric means. The results obtained are presented in Table II. The calculations do not have the same degree of validity as they do for surface samples for several reasons. First, radioactivity was measured by lowering the probe through the water column and not on the actual samples brought to the sur- face for coliform analysis since these samples were too small. Because of the non-homogeneous nature of the water mass and drift of the ship around the station location during sampling, the actual radioactivity of a sample could have differed greatly from that read from a depth curwe. Second, dilutions of greater than about 1/300 calculated from chlorinities are certainly grossly inexact, and dilutions of greater than 1/2000 are com- pletely indeterminate. The data presented above should be viewed with these limitations in mind. From the data in Table II, it can be seen that a greater dilution of the tagged effluent occurs than one would calculate from chlorinity, indicating, as with the surface samples, that ( Meow i 16 TABLE II Calculated Dilutions and Calculated and Observed MPN's of Subsurface Samples Number of Calculated from Observed samples radioactivity chlorinity MPN's/m1. Geometric mean 12 1/640 1/160 of dilutions Geometric mean 20 790 70 on MPN‘'s/ml. 11 3,600 170 Fabs A Dat es ae 17 dilution of fresh effluent with older effluent is occurring. The calculated MPN's are higher than the observed ones showing again an extra disappearance of coliforms in addition to that due to dilution. Assuming sedimentation to be an important factor in the extra disappearance, one might have expected the observed subsurface MPN's to be higher than the calculated MPN's, at least in some individual instances, since one might expect to trap settling particles in some of the subsurface samples. Actually, three out of the twenty subsurface samples had MPN's that were higher than the calculated, and in four instances, subsurface samples having higher counts than the water above them were observed. These limited observations provide some evidence for the occurrence of sedimentation which was evident aS a cause of coliform disappearance in the vicinity of the Orange County outfall (May 1 report). Dye Patch Experiments In addition to the two dye patch experiments done on the tracer cruise, six additional were run on three other trips during which primary effluent was being discharged from the Hyperion outfall. The MPN*s obtained are plotted against time for each individual run in Figure 5, and the geometric means of the MPN‘s of all the runs against time in Figure 6. The time for 90% reduction in coliform count ranged from 13 hours for the most rapid to 43 hours for the slowest with 3 hours as the average. The last value is the best estimate available for the rate of disappearance to be expected around the proposed new outfall assuming the same type of primary effluent will be discharged. ihn Figure 5. 18 The MPN of coliforms versus time for primary unchlorinated effluent. Nes, 4 min. 30 sec.- 90% Reduction 0 2 4 6 8 10 l2 OME WIN ih @ Wes 19 Figure 6. MPN of coliforms versus time for the Hyperion and Orange County outfalls. Af 7 ay anietidos TW ANdIW o—Dye pate data — Hyperion x— — Orange County a—Grid data — Hyperion Hyperion—90% Disappearance = 3 hr. Orange County 90% Disappearance = |% hrs. 2 4 6 8 10 l2 IME Nie @ WES {9 HY al PORES re Par a reat sil y rip ccd byopcoyrinry soit yee 6) Rei 20 The comparable data for the vicinity of the Orange County outfall are also plotted on Figure 6 for purposes of conparisieay the average disappearance rate for this area being 90% in 13 hours. In an effort to determine whether or not the dye patch experiments gave data that were representative of the entire effluent field, experiments were run at Whites Point and at Hyperion (during discharge of secondary treatment effluent) in which a large number of samples were collected over a closely Spaced grid (1,000 feet on a side) located within the sewage field. The results of these experiments were discussed in the May 1 report. The same type of experiment was done on three Separate occasions during the discharge of primary effluent from the Hyperion outfall. Two grids of 25 samples each, spaced approximately 4 hours travel of the field apart, were run on each trip. The individual counts in the grids showed the same type of distribution as was shown for the two previous Hyperion grids (May 1 report), with most of the values for any grid clustered around the geometric mean. The geometric mean of the MPN's of the individual grids are plotted on Figure 6. It can be seen that, with one exception which was low, the means fall remarkably close to the curve representing the average disappearance rate determined from the dye patch experiments. These data are further confirmation that the dye patch technique gives a representative picture of the behavior of the effluent field. The question as to whether the fluorescein used in the dye patch experiments exerts a toxic effect on the coliforms present waS previously considered. Experiments were reported (May 1 pees ‘ oe Ca oe ‘ oy nt ri “f ‘ ‘bal xe ny . ” ; ; : ‘ yank SE BRT Made TOY CHRD Re ATG 21 report, p. 66) that showed no dye toxicity. These experiments were run in the absence of direct sunlight and the possibility existed that a toxicity due to a photodynamic effect could occur. Consequently, toxicity of fluorescein was retested taking this factor into consideration, but no photodynamic effect could be shown. The results of one experiment are presented in Table III. Subsurface Distribution of Coliforms Thirty-four stations were occupied at which a series of one surface and three subsurface samples were collected and analyzed for coliforms and chlorinities. The profile con- structed from one series of stations is shown in Figure 7. As with the previous data of this nature discussed in the May 1 report, the highest subsurface counts occurred along the general lines of movement of the surface effluent field. The tongues of high coliform content extending down from the sur- face that were so prominent in the Orange County data did not show up as strongly in the data taken in Santa Monica Bay. There were individual high subsurface counts in areas of normal chlorinity that did suggest sedimentation as was discussed above in connection with the subsurface radioactivity measure- ments. In general, the evidence for sedimentation as an important factor for coliform disappearance was not as strong in the Santa Monica Bay area as in the other areas studied. This could relate to the lack of steady state discharge of unchlorinated effluent into Santa Monica Bay. Since unchlor- inated sewage was only released for a few hours on the days i > ea \ HTK, i ’ is ay wise 7 G a: ea R: ot, ie Sey LAG iin ; allie 22 TABLE III Effect of Fluorescein on Coliform Organisms in the Presence of Direct Sunlight1 MPN/m1 MPN/m1 Time with dye without dye Time with dye without dye O hour 24,000 24,000 4 hours 2,300 23 72,000 72,000 : 620 6.2 2 hours 2,300 2,300 6 hours 230 0.6 25300 230 230 nil 1, A mixture of 5% unchlorinated primary effluent in sea water with and without 0.01% sodium fluorscein was used. A 500 ml mixture in an open beaker was exposed to sunlight for the time indicated. MPN*s were determined by Standard Methods. 23 Figure 7. Vertical distribution of coliform bacteria at the Hyperion outfall on April 17, 1956. yet i ney er PROFILE MPN/ ML. BACTERIAL oO 2 Oo 4 Oo o 2 oO ee) - 1 l I oo oO oo Oo oe = = = oO oO So oo own Oe Oo o SS So. Ns al ee IR KON) 1771V4LN0 24 of the trips taken, most of the solids in the bay at these times were from chlorinated effluents and would be expected to contribute little or nothing to the subsurface coliform counts. Bureau of Sanitation Results Previous to the May 1 report, there had been an extensive discussion of the apparent discrepancies between the disappearance rates we observed using the dye patch technique, and the rates found by the Bureau of Sanitation using a different type of field procedure. This problem was discussed in the May 1 report (p. 64-71) and it was concluded that the differences in results were independent of field or laboratory technique and related only to differences in the nature of the effluents being studied. Most of our work was done on primary effluent from Orange County and most of theirs on secondary treatment effluent from Hyperion. This conclusion has been substantiated by the more recent data collected by them and us during periods: of discharge of primary effluent from Hyperion. Without detailing the Bureau of Sanitation data, which are summarized in their “Summary Report, Oceanographic Investigation of Santa Monica Bay, July 1956", it is sufficient to point out that they show an average 90% reduction of coliform rate of 3.4 hours for the first nine hours after discharge as compared to our average figure of 3 hours for the first 6 to 10 hours after discharge. Further, on a single trip to the Orange County area they found a disappearance rate identical to that given in the May 1 report. ae ye Aes r Te i oy Vu an f (reed 0 25 After nine hours from the time of discharge, the dis- appearance rate measured by the Bureau of Sanitation changes sharply and is of the order of 15 hours for a 90% disappearance of coliforms. This value is based on samples collected close inshore near the surf zone and it "is believed to reflect the boundary effects obtained in and near the surf zone where the coliforms undergo a much slower rate of reduction than in off- shore waters". This same effect is reflected in the persistence of the beach counts observed on several occasions by the Bureau of Sanitation after the release of unchlorinated secondary treat- ment effluent for short periods of time from the Hyperion plant. The less rapid disappearance of coliforms in the surf zone was previously discussed (May 1 report) and it was pointed out that if sedimentation is an important factor in coliform disappearance, it would not be operative in the surf where turbulence would keep particulate matter in suspension. In fact, the breaking up of particles in the surf might in effect increase the apparent MPN's of the beach samples. The major significance of this effect is merely to shorten somewhat the time of travel available for effective coliform disappearance. In other words, the time of travel to the surf zone and not to the beach is the signifi- cant one. The difference between the two times, however, is small. Summary of Water Data The rate of disappearance of coliforms discharged from three ocean outfalls was determined by following patches of effluent tagged with fluorescein dye. The general similarity ot, Ree om oy a ieee Loot la eee ed i hy A ni ditto aveebg tog: 4 “f i tt ae bs oo) ey Te pe Vine TUR te tae eo " ” AD a 1 ae ae thokvig sods tol dna ade iy 1 FIG ORS Mi “ ad at Misc, vere i, } - Peay a ; - LS aguie © 26 between data obtained by this method and by three other indepen- dent methods, (using a radioactive tracer, running traverses across the sewage field, and running detailed grid patterns in the field) shows the validity of the dye patch procedure for determining the fate of coliforms in an effluent field. Calculations based on dilutions of effluent measured by radioactivity showed that even in effluent of very recent origin from an outfall, there is a greater disappearance of coliforms than can be accounted for on the basis of dilution alone. When Similar calculations are made using chlorinities as a measure of dilution, the extra disappearance over dilution is much greater, showing that fresh effluent undergoes considerable dilution by older effluent in the vicinity of an outfall. Data obtained from subsurface samples taken below the main effluent field show that sedimentation is an important factor in the extra disappearance of coliforms. The data available were not sufficient for a precise measure of this effect and it is not certain whether die-off of coliforms and other factors are also of significance in the extra disappearance. The disappearance rate differed with each type of effluent studied, being most rapid for the Orange County effluent and least rapid for the Whites Point effluent (although data on the Whites Point area are fragmentary). Primary effluent from Hyperion shows a more rapid rate of disappearance than secondary. The rate of disappearance may be related to the solid content of the effluents and their settling characteristics. The average value obtained for the Hyperion primary effluent, 3 hours for a 90% disappearance, is a reasonable one to employ for calculating ee fuss i * ‘ A Sy ign vi if ¥ wah fy 5 S225 4. F moehae agi hia ote 27a Ee vi it ca cog & ; ian” § bhi a th oii Nenu peretr) 4h f & E oh’ “ot Le 7th eh ere ; edhe LT ORE 07 27. performance of the proposed new outfall in Santa Monica Bay, if unchlorinated primary effluent of the type studied is to be discharged. Disappearance is less rapid once the effluent reaches the surf zone. This is explainable, if sedimentation is a major factor in removal of coliforms on the basis of the elimination of settling by the turbulence in the surf. In effect, it is only the time of travel from the outfall to the surf zone, and not to the beach, that is of importance in coliform disappearance. CONCLUSIONS WITH RESPECT TO STATE STANDARDS In the "Decision dated May 2, 1956, of the State Water Pollution Control Board" standards were set for the "waste discharges proposed by the City of Los Angeles in its June 13, 1955 report. . .“ Of the standards set, only two refer to the permissible coliform densities and the question to be discussed in the following section is whether, in the light of the infor- mation available, they will be met. The non-bacteriological aspects of the standards will be dealt with in other sections of the final report. In the specifications, the area around the proposed outfall is divided into three areas, each protected for different bene- ficial uses. Area 1 includes waters within 5,000 feet of the nearest sludge or effluent outlets; Area 3 comprises the waters between high-water line on the beach and a line 1,500 feet off- shore from the high water line; and Area 2 the waters not included in Areas 1 and 3. For purposes of sampling, eight traverses were established that ran radially outward on specified oes OR ie i ty re gait re 4 fee “" suis sigh wh pian fan tonite bo va mot ve ) nee am fy or jit esate Moy Lavere i 28 bearings from the point of origin. On each traverse there is an A station within Area 1 and B and C stations in Area 2, the locations of which are within specified distances from the point of origin of the traverse. In addition, there are a series of shoreline stations located at not greater than 10,000 feet inter- vals for a distance of 14 miles north and 9 miles south of the Hyperion plant. The bacteriological standards laid down specify that as determined by the B and C sampling stations "The coli- form concentration, aS measured by the geometric mean at the two sampling stations along each radial traverse, shall not exceed 100 per ml in any three consecutive samples or in more than 20% of any 20 consecutive samples.” As determined at the shoreline sampling stations, “The coliform concentration at each sampling station shall not exceed 10 per ml in any three consecutive samples or in more than 20% of any 20 consecutive samples.” From the information available on currents in Santa Monica Bay, it can be assumed that the most rapid currents observed along any traverse will be no greater than the maximum rate observed along any other. This does not imply that the effluent will spread out equally in all directions, since the data have shown that a well-developed current system exists in the bay (see Final Current Report), but it does imply that the maximum danger of noncompliance with the standards will be along the traverses of minimum length and consequentiy of minimum travel time of the effluent from the outfall to the established stations. On this basis, traverses 2 and 3, which run most directly towards the beach are the most critical ones. Along these traverses, the B stations can be located between 13,000 He an i, ie? « BE kite ¥ 10m i 29 and 17,000 feet from the outfall, and the C stations between 23,000 and 27,000 feet away. For the purposes of the further discussion it will be assumed that the B stations along these two lines are 3 statute miles (15,800 feet), the C stations 5 miles (26,400 feet), and the surf zone 53 miles (29,000 feet) from the outfall. In order to make any predictions, the following information must be available; (1) the rate of disappearance of coliforms, (2) the initial coliform content at the boil, and (3) the rate of travel to the surf zone (or any other point away from the boil for which prediction is desired). Each of the above factors are variable and aithough average values can be assigned for each, the extreme situations must be considered as well as the average situation. The average disappearance rate of 90% reduction in 3 hours can be accepted as typical under the conditions that we studied. No individual dye patch showed a disappearance rate of greater than 43 hours for 90% reduction, and this value is therefore used for the “worst" situation. It is possible that slower rates might occur on some occasions, but there is no way of predicting the frequency of such occurrences from our data, if they do occur at ali. Various estimates can be made of the coliform population at the boil depending on the data employed. Ome could accept the geometric mean of the twelve samples we collected in the boil during discharge of primary effluent, 36,000/ml, as also applying to the situation that would exist around the proposed outfall. However, since an initial dilution of at least 1/60 is 30 expected from the proposed outfaiil, and an average dilution of only about 1/25 (based on radioactivity measurements) occurs around the existing outfall, the above value should be corrected by a factor of 25/60 giving an average value of about 15,000/m1 for the proposed outfall. One could also use the MPN‘s of the primary treatment effluent per se and correct these for the expected initial dilution. Plant data, summarized by the Hyperion Engineers, give the following values for the coliform content of primary effluent: 259,000/m1, as the geometric mean of 257 grab samples taken over a year's period at the same clock time for each sample; 561,000/m1 as the geometric mean of 24 samples taken over a 24 hour period; 389,000/m1 as the geometric mean of a similar series taken over a different 24 hour period. Applying the factor of 1/60 as the minimum expected dilution, the above values would yield coliform densities at the boil of 4,300, 9,400, and 6,500/m1, respec= tively. Using the boil counts obtained on the tracer cruise, calculating back to the initial count of the effluent (see Table I) on the basis of radioactivity, and again assuming a minimum dilution of 1/60 at the boil for the proposed outfall, a boil count of 12,000/m1 is obtained. The highest and lowest estimates from these data differ by a factor of four which represents a little less than 2 hours disappearance time at the rate of 3 hours for 90% disappearance. The highest value, 15,000/m1 at the boil, is arbitrarily accepted as the average 1. This is the figure cited by the Hyperion Engineers as resulting from Dr. Brooks’ studies on the design of the proposed outfall. A larger or smaller value would change the calculations propor- tionately. rot Fay fet eeloiae 6 way Tes ih bee f \ ‘9 31 count to expect, since this is the safest assumption that can be made. The count at the boil could be higher than the figure chosen if either the estimate of initial dilution is too high, or if the coliform content of the primary effluent is higher than the figures cited. Although reasonable estimates of the "worst™ situation are difficult to arrive at, one would not expect any appreciable volume of a primary effluent to have a coliform content of greater than 2,000,000/m1, nor would one expect the proposed outfall to give a lower initial dilution than the present outfall, or 1/2156 Using these two values for the worst situation that might exist at any time at the proposed outfall, a value of 80,000/ml is obtained for the boil count. Using the average and worst values arrived at, one can calculate the expected coliform count at any time of travel from the outfall. In Figure 8 is a graphic presentation of these calculations. From these curves it can be seen that movement of the water to the surf zone in less than 95 hours is required before the State Standards for the beach would be exceeded under averaged conditions of initial coliform popu- lation and disappearance rate. The comparable figure for the worst situation envisioned is 173 hours. These times corres- pond to critical current velocities directed towards the beach of 0.58 and 0.31 statute miles per hour, respectively. At these velocities the calculated geometric mean of the B and C station counts are 72 and 100, respectively. In other words, if the beach stations meet State specifications, then the B and C stations will also comply. ee Bs ‘\y uh se a ; tat y, CT aa ee eae) mo ah é A A Figure 8. The MPN of coliforms versus time of travel from the outfall. 32 > hours for 90% disappearance 80,000 /ml. at the boil ro) b ° w \ \ \ 9.5 Hours 17.6 Hours 3 hours for 90% disappearance IW SZ SWYHOAITNIOD JO NdW ro) 15,000 /mi. at the boil \ 0 lO 20 2aViEw@ Et A\N/ EL ROM QUT EARS ee, Oy ae “4 3 i bY Lok on 33 The current data obtained during the bay survey is dealt with in an accompanying report and will not be considered in detail here. However, an inspection of the drift card returns show that the great majority of the cards released at the sites of the proposed sludge and effluent lines required considerably longer than 24 hours to reach the beach, if they were carried ashore at all. Actually, only two required less than 24 hours, the times being 21 and 18 hours, respectively. Even this rate of movement would not result in beach pollution under the worst set of conditions assumed. Therefore, on the basis of measured currents around the proposed outfall sites, one must conclude that there is an ample margin of safety as for meeting the coli- form requirements set down. It must be pointed out that velocities of greater than the critical ones cited above were found in the bay. Indivi- dual drift cards released on 2 of the 13 trips had velocities exceeding 0.58 miles per hour, and on 4 of the 13 trips exceeding 0.31 miles per hour, with one cruise (Aug. 20 and 21) not included. For the most part, the high velocities were from cards released im the inshore stations, particularly those towards the south end of the bay. In some of these instances the cards did not move directly to the beach, so even though the velocities were high the actual time of travel in the water would have been sufficient to reduce the coliform population below the specified maximum. However, many cards of high velocity traveled directly towards shore. If sustained currents towards the beach of greater than 0.58 miles per hour were observed more than 20% of the time, bak via bp Fy We : i a ; oe Ph BC ee re as a | xy By i, 7ae ie AR. @ fir 4 |, OR PeA ARE O ALD enc i raMn ee ert on 34 non-compliance with State Standards would certainly be expected. If, however, sustained currents of greater than 0.31 miles per hour towards the beach were found 20% of the time, the possi- bility of compliance would still be good since extreme conditions were postulated to arrive at this “worst” value. From the current data available for the proposed outfall stations, one can only say that neither of these conditions seem to prevail, taking the year’s measurement aS a whole and, therefore, general compliance with State Standards would be predicted, However, if conditions at the inshore stations are applied to the proposed outfall positions, compliance is dubious. One further point needs discussion, and that is the speci- fication that no three consecutive samples at any single beach station should exceed a count of 10/ml. If the temporary exis- tence of a high velocity current brings a slug of effluent into the surf zone in less than the critical time, then the slower rate of disappearance of coliforms in the surf could result in excesSive counts for periods much longer than the existence of the current. For example, 24 hours of a sustained current of greater than 0.58 miles per hour toward the beach could give high beach counts for as much as 48 hours thereafter. Chlorie nation of the effluent being discharged subsequent to the initial 24 hours would not be effective in remedying the Situation. Since currents of this velocity have been measured on occasion, one must anticipate occasional difficulties in complying with the above standard, even though the frequency of such occurrences is low. amy sf » out 35 In final summary then, the data indicate that an ample margin of safety appears to exist for complying with State Standards on an overall basis. They do not, however, rule out the possibility of restricted periods of non-compliance. COLIFORMS IN THE BOTTOM SEDIMENTS Introduction Previous to the May 1 report, two series of bottom samples were collected in Santa Monica Bay and analyzed for their coli- form population. Less intensive sampling was also conducted in the vicinity of the Whites Point owtfall and around the Orange County outfall. In all three areas, coliforms were found for considerable distances around the outfalls. The numbers obser-= ved were variable and samples taken at approximately the same location near the Orange County outfall gave widely different coliform counts. It was believed that part of the variation was due to difficulties in the sampling technique, in particular the difficulty of capturing all of the uppermost sediment layer where the coliforms should be most abundant, using either the snappers or the coring instrument (May 1 report, p. 53-57). As a consequence, a new Sampling apparatus was developed and the coliform populations in the sediments were reinvestigated. Sampling Methods Samples were collected by two procedures, either employing divers or else using a specially-designed bottom sampling apparatus. The divers were used for the inshore samples that 36 could not be reached by ship. They were provided with glass tubes open on both ends, about 2 cm in diameter and 6 cm liong, having a cross-sectional area of 2.5 cm?, These were filled with sterile water and closed with caps that fitted over the ends of the tubes. To take a sample, the diver removed the caps, pushed the tube into the bottom, and then replaced the caps. Although a somewhat variable depth of the sediment column is taken by this procedure, the entire surface layer is captured, and this layer is the significant portion. When the capped tubes were returned to the divers’ launch, their entire contents were transferred to sterile water blanks of proper volume to give an initial dilution of 2.5 em /100 mi of surface area of sediment. From this initial dilution, further dilutions of ten fold increments were prepared and coliform contents deter= mined by Standard Methods. The counts were calculated on the basis of MPN's/cm@ surface area of sediment. The sampling apparatus used from the VELERO IV is shown in Figure 9, A vial of 2.5 cm? cross-sectional area, filled with sterile water, is inserted into the vial holder while the sampler is in an inverted position. The apparatus is then cocked, bringing a metal plate across the mouth of the vial, which closes it. The sampleris turned upright, maintaining a tension on the cable during this operation, and then lowered to the bottom. When the foot of the sampler hits the sediment, the plate pulls back allowing the vial to penetrate a cm or two into the bottom, depending on the type of sediment. As the cable is wound in to retrieve the sample, the plate closes, Sealing the sampie in the viai. When the sampler is brought i ve 1% Ki Si Som % Ln on or eb * : mabe tats iy a on bapeniptie o1py awa wen -eabojtrom fealbiate rm ate bestia yaa. dabeaosese ‘mea tay t aa 0 hae 4 , wet) anit roi Het a wink Beberekt. ee, eu wth atHdt as, ari oe (omits Let bas remit 1p Re: ab bane wnt ‘te arin art ae ‘winds hata ogi a snbae bred chagatgn ‘ibaa Wiener) ah) mead Derive t iivoeht ba Cede bs a mein: field ries ba a ne chaxverd Loa e ‘ a iG it nba bul wet parti des eo if wg anton, cy bk a nit oe | ne mit iat thewk Bae hia ae wi C Hi gerne Es ef Ht ie ott i eysivky re i sitiense wi site ot, wear 37 Figure 9, Bottom sediment sampler for obtaining samples for coliform determination. Designed by Dr. K. O. Emery, and constructed by Mr. Alexander Campbell, Chief Engineer of the VELERO IV. : d Sie) PAINS Chey! 38 on deck, it is inverted, the vial is removed, and the vial contents are introduced into a sterile dilution bottle. The procedure from this point on is the same as with the diver samples. Results Using these techniques, 100 samples were collected in the vicinity of the Orange County outfall on a series of parallel lines from about 13 miles down coast to 3 miles upcoast from the outfall. On each line, one sample was taken at the water line, one in the surf, and the remainder spaced out to three miles offshore. Most of the samples to a depth of 60 feet were taken by the divers, the deeper ones being collected from the VELERO IV. On several stations samples were collected by both techniques and these showed similar coliform counts. Using the same procedures, 110 samples were taken in Santa Monica Bay in a Similar pattern. After the bacteriological aspects of the bay project were completed, a similar series of samples were taken in the vicinity of Whites Point using funds provided by the Los Angeles County Sanitation Districts for the trip. The data from this trip is included in this report with their permission. a Table IV summarizes certain aspects of the data obtained and Figures 10, 11, and 12 map the extent and intensity of the bottom coliform fields found in the three areas. It can be seen that the coliform fieids around the Orange County and Whites Poing outfalls, where unchlorinated effluent is constantly dis- charged, occupy an extensive area and contain large numbers of PTET CAN te s Li est) Gee TABLE IV 39 Coliform Bacteria in Bottom Sediments Location Orange County Santa Monica Bay Whites Point Number of samples 100 109 106 Number positive 83 9 72 Range of MPN/cm2 nil to 25,000 nil to 250 nil to 92,000 ia PR 40 Figure 10. Bottom coliform field in the vicinity of the Whites Point sewer outfall. 6000 100-1000 E4] 1.000-10.000 fq MPN COLIFORMS / CM? 1000 fo) peur ie t ie WN 41 Figure 11. Bottom coliform field in the vicinity of the Orange County sewer outfall. -. 7 te YsENIIIV BH Bz bfoii atPELon motto -tieiieo ..ewsa yinue sgaas0 . { Sy / |i gv iy) AA aN WO/Nd wuodito> OS> 002-0S 008-002 000E-008 000’ZI-000E 000’2I< Ll 62 ks fo 9S61 Wddv 222 L774 NI SYNOLNOD SS HOV3IG NOLONILNAH 1334 0006 OOOE O oOOood€ SATIN 3LNLVLS 2 I VI¥aLOVa WOLLOE ALINIDIA CGNY NE! LadOdMaN {o) ! { 100 9| Eee trsi|lis | | IvsS 19S 18S cs i, ; zi HN aes ree Fe Bra Mist ena | RL wip ein Sel a RR A eae vigil i ey 1M : Iny ; f 42 Figure 12, Bottom coliform field in the vicinity of the Hyperion sewer outfall. ie we! by yaa ey Red SOND N8°28- 26’ 2yv rn | a ie EL SEGUNDO COLIFORM BACTERIA IN BOTTOM SEDIMENT ° Ae =a —— STATUTE MILES CONTOURS IN FEET 2,4 = MPN / cm? © MUL HY PERION ANHAT TAN BEACH 118° 287 Fr ell epee sey A\ Piste, Fey p R . y Tey ; f hom, Sey ines } ‘ ies ikea ak Lio ea ne Sian a gh 1 sell ic SYN e EMIRATE yA) : f w 43 coliforms. In the vicinity of the Orange County outfall the highest counts were observed down coast from the outfall and extended to the beach. One sample, taken at the water line about 3,000 feet down coast from the outfall position, had a-- MPN of over 5,000/cm*. It should be mentioned that this sample, as well as other high count samples, appeared to consist of clean sand with no visible evidence of sluwige deposits. In qualitative terms, the distribution of coliforms in the sediments appears to follow the movement of the surface effluent field on the days of our trips to Orange County. The distribution of coliforms in the sediments around Whites Point differed somewhat from that observed at Orange County although an equally large, if mot more extensive, field existed. The highest concentration of coliforms followed a line travelling up coast from the outfall parallei to the shore and rounding Point Vicente, and down coast and seaward past Point Fermin, The data also showed coliforms off the entrance to the harbor which could have come from the outfall discharging inside of the breakwater. Contrary to what was found around Orange County, however, the waterline samples, with two exceptions for the stations directly behind the outfall, were negative. The distribution of coliforms in this area generally coincided with the distribution of three other markers of high organic matter content undoubtedly of outfall origins the distribution of black sediments; the distribution of HS in the sediments; and the distribution of Chaetopterus variopedatus (Figure 13). — on i 1 sR), res es Ait, chap! in, iat ‘Ea ny tebe Sen rte be wan BN ne ev veal Coe steely tate 'g oat ot) “ aoa CS salt tho, ‘tat ip he ny tinge bean’ “nt ett : hy gece bntaxe wide ht’ ae iat mith, Sek :! Altes tte: ‘dete 00 . fe ‘macy ba eae oh i Phe ifaw wi aint sl sehen oe Mis, api fh) oan 4 | Phar! ee Gan? Lt 0 ae poate" se Honing i i 44 Figure 13, The distribution of black sediment, hydrogen sulfide, and Chaetopterus variopedatus in the vicinity of the Whites Point sewer outfall. i} P m Pie ey iat w DG 7 f 0009 SNAIAVGSdOCIYWA SNYSALdOLAVHD Se qWas INSSCseegNr LNAWNICSS MOV 1a JES 2) Nil SQINKeWN/ers! loss 45 In addition to coliform determinations, samples were used to enumerate enterococci by the molecular filter technique (these determinations were made by personnel from the laboratory of the Los Angeles County Sanitation Districts, who were present aboard the VELERO IV). The data obtained is contoured in the same fashion as the coliform data (Fig. 14). A comparison of the two sets of contours shows that there is a reasonable similarity between them down coast from the outfall where an area of relatively high counts of both types of organisms extend past Point Fermin, In the uwpcoast direction, correlation is not as good. A series of apparently isolated highs of entero- cocci were found whose course is along the continuous tongue of high- coliforms found in this area. Whereas the coliform contours strongly suggest the outfall as the source of all the coliforms in the area (excluding perhaps the high pocket just offshore from the Oceanarium and the pocket off the entrance to the harbor), the discontinuous nature of the enterococci distribution might suggest multiple sources of these organisms. When the coliform coumt is plotted against the enterococci count, the most apparent relation is that the majority of the Samples (excluding those where both counts were nil) have coli- form counts ten or more times the enterococci counts. There is no constant ratio between the numbers of the two types of organ- isms, nor is there any obvious trend of either increasing or decreasing ratio with distance from the outfall. It has been suggested that a comparison of coliform and enterococci counts might provide a basis for distinguishing between fecai and non- fecal coliforms or between coliforms of recent or older origin. > pie! 1 ANT)? ata Lee oy ‘bags bak tie } tha’ rh 2 ae b edt S22 9TH from. | Syane, Figure 14, 46 The distribution of enterococci in the vicinity of the Whites Point sewer outfall. 7 ' 47 In contrast to what was found in the other two locations, only a few of the sediment samples collected in Santa Monica Bay showed the presence of coliforms, and in these samples the numbers were low. This is what one would expect considering that essentially all the effluent discharged in the area is chlorinated. However, a comparison of Figure 11 with Figure 15 of the May 1 report shows that in areas where positive samples had been obtained previously, negative ones were found on the last survey. The only reasonable explanation for this situation is that the coliform fieid in this area is either transitory timewise because of only sporadic discharge of large coliform populations, or else is very unevenly distributed. In examining the samples taken from the Santa Monica Bay area on the last survey trip, it was found that a large number of positive lactose broth tubes failed to confirm on EMB agar. An effort was made to determine the cause of these "false posi- tive" tubes. Although the work could not be completed because of lack of time, it was found that at least part of these faise positives were due to lactose fermenting aerobic and anaerobic spore formers. More important, it was found that a high per cent of the positive lactose tubes that did not confirm on EMB gave positive results when transferred to brilliant green bile broth. Further examination showed that these positive brilliant green tubes did not contain coliforms. Although these findings do not bear directly on the question at hand, they certainly indi- cate that the use of brilliant green bile medium for confirmation test should not be considered in any project dealing with marine sediments. Pa ad 48 Discussion The presence of extensive coliform fields around the two outfalls where unchlorinated effluent is now being discharged makes it appear certain that a similar field will be built up around the proposed new effluent line in Santa Monica Bay. Considering current directions and the volume of solids to be | discharged, there is every reason to believe that the coliform field will eventually reach the beach zone as it apparently has around the Orange County outfall. The expected occurrence of such a field raises several important problems that will be discussed in turn. Since there are at present no specifications relating directly to the coliform content of the sediments per se, the question of compliance or non-compliance with State Standards arises only indirectly. In attempting to explain the occurrence of high beach counts in the vicinity of the Orange County out- fall in spite of the rapid disappearance rate for coliforms measured in that area, one possibility proposed was that the high counts might be related to the disturbance of the bottom coliform fieid during periods of strong wave action (see May 1 report). This proposal was put forth before the full extent of the coliform field in the sediments around this outfall was known and the subsequent finding of relatively high counts even at the water line certainly made the idea more plausible. If one accepts the conclusion that a similar field wiil be bwilt up around the proposed Hyperion outfall, then the possibility that bottom coliforms might contribute to the beach counts must be considered for the Santa Monica Bay area also. Actually there wut ; i aed!’ fp Te hee r a My 49 is no direct evidence available in favor of this hypothesis, and at least one instance is known where this situation might have been expected to occur and did not. During the past few months there were at least two occurrences of high counts all along the Orange County beach during periods when wave action was not intense, and one occurrence of a high surf from the south for two successive days without any surge in beach counts. All one can conclude from these limited experiences is that aithough the possibility exists, the likelihood is uncertain. Aithough at the present there are no specifications in regards to the coliform content of the sediments, it could be argued that some of the beneficial uses protected in Area 2 and Area 3 might be impaired by their presence on the bottom. This would be especially true if there were indications that the presence of coliforms in the sediments could have a public health significance, It can be argued that if coliforms are present, then pathogens might equally well be present, and could be carried into the water under proper conditions of turbulence. The only countering arguments would be that coliforms survive longer in the sediments than pathogens, and the latter have not been detected in marine sediments. Unfortunately, the arguments either way are without substantial experimental foundation at the moment. Both the water and sediment data indicate the possibility of a much longer persistence of coliforms in the marine environment than most investigators previously suspected. However, the question as to exactly how long they can survive or whether they can even multiply (especially in the mud) remains unanswered. As far as pathogens are concerned, the author knows im: seh Ha RG ek OR: tak ee RA Raa Sas nd RRR rr 50 of only one attempt to recover them from the sediments off our coasts, and that was the work cited in the May 1 report in which examination of 70 sediment samples from Santa Monica Bay for enteric pathogens proved negative. Certainly, considering the importance of the question this is not an adequate sampling, since from what is now known one would choose either the Whites Point or the Orange County areas for such a survey. It is not the intention of the author to attempt to anti- cipate any action on the part of the Water Pollution Control Board which might result in the establishment of coliform standards for the sediments. In terminating this discussion, however, I would like to express two opinions; first, there is at the moment insufficient evidence pro or con to decide whether such standards are necessary; second, that every effort should be made to obtain the information necessary for a considered decision. Summary It has been shown that an extensive coliform field exists in the sediments around the Orange County and Whites Point out- falls where unchlorinated effluent is being discharged constantly. Although coliforms have been found around the present Hyperion outfall, it is believed that their occurrence is either tran- sitory or else that they are unevenly distributed. It is pre= dicted that a similar coliform field would build up around the proposed new outfall and ultimately extend to the shore. The possibility that coliforms in the inshore sediments could contribute to the beach counts in the water during periods of , da a I a fh sche hey : a ve 51 heavy wave action exists. However, from the available evidence this occurrence appears remote. The question as to whether the presence of coliforms in the sediments has a public health significance has been briefly discussed, It is the author's opinion that our current infor- mation is too fragmentary to allow a reasonable answer to this question. cai Ae j itty hh at 16M mane at dunahans | THE FATE OF COLIFORM BACTERIA IN THE VICINITY OF THE ORANGE COUNTY, LOS ANGELES COUNTY, AND HYPERION SEWER OUTFALIS An Interim Report Department of Geology University of Southern California May 1, 1956 OT wee Ne Wee a ee ae) » ORE TEAST QO Wen ee DS Ae rae omny TABLE OF CONTENTS ENIRGDUGIAON citclcteinele cioteicicitialcieielcle/eleicialcisiclersiete elalsiolalovelalaiaiclols/avotelalelctelall™ BOTTOM SEDIMENTS IN THE OUTFALL ARBAS.. ccc cen ccc cc ccccosvcescccd WIEECOS PON ta s\cic!c o1/s/ela\n celle 0) 00's ole cle sl elcieie s/s eicieiole siela cle cleleic\cle/a> Orange) County cicclelcs cicicvicialcicisviales salsio'¢ ole siaceccs seca ceconcicl Santa) Monica Bayccojiciciceciceceoccieiccioceousicoeeice coco cool, OCEANOGRAPHY NEAR THE OUTFALL AREAS ccc. cocccccccccce ccs ccceccooll Sallis ride cree ers orators oe Seth nic lals ioe asian neleeromeilacaerselsee ll Orange) Couniiyjcccccccccccc cociecolscels occa seco ciecolul HYPeY1OMNcccccc 000 c0ce coc cle ccs coc coe ccencocecceccocels Whites) Point Temperature CharacteriSticSccccecccoceo coc cvcccececccccccol| Orange County Outfall Areaccecccecccccccecceccoccccccel! Whites Point Outfall Areaccoceccccccccccccccccceccc col Hyperion Outfall Areaccocoocceccccceccccceecccovesececcld SUMMALYio o1c e10.0:0:0'0:0\010. 0-0 10 0\e c olaicleis cocoa cece cece cco eseool® WATER MOTION IN SANTA MONICA BAY .cccaccoaccscacccccecceccccc0e eon COLIFORM BACTERLA DISTRIBUTIONS ccs siecle clos eccisosioeciasslsccoccece tlt Field Procedures. cc00c0ecc1c0000cceecess00ee0l 0 cvececec cool! Dye Patch Experiments... cccccccecccs cossccecseicovic cic coll! Surface and Subsurface Samplingsocceccecceccceccecccel5 Sediment) Sampldnecic occ 0c clos cle/ais'e ole slelcle clelolaicleleielslcleleeiciee O Laboratory, Proceduress oicicic'cc10\c:c\cicie cleloielcicisicleiereisiclsleieieleiciosicia tO Determinations of Most Probable Numbers (MPN ) of ColeibhommsilorstsisieveloiclelciseleleleloreloieleielaloioleveisteterercrersiaeO IdentiniicabionsoLecolsthormslccioclolcojoeoleclelelolcelsreielciaiceciale Enteric RAGHo pen Sictclavelelcioleieteetolcielollclaiolerateielerseioretaisleteisiniore eo ; ; ; ' : 7 ty a | Me Eka oh) oi, citar icin trret ex y hsp ae iy a Le SUCAT ML 3 bf " : ‘ ry rae : ary oe eo ae if u we Lay ‘Pind & lal Disappearance of Coliforms with Time (Dye Patch Exp riMeMmtD relelasleicicisioluieiele eieieielslelelevojere/eieiciewiciols eleieielO Effect of Dilutionescocccccccccscccccccccccccccccccccccscece te Surface Distribution of Cold formsic cise cicie cies cecs ecleciecisics cicleSO Subsurface Distribution of ColiformS.ceccccccccccccocscoccoll] Coliforms in Bottom SedimentS.ccccceccecccscccccscvcceceeeed3 MabenoliG Olt OEM Bieelelatelelelalelelelereleleleisic(eicielsleleiajeteie eleicleleie elersielcre ister (| Orange Coumty Beach Oount Datacesceciclccicccicciciciccus cisicccescDo Les Angeles Sanitation District Dataeccssccecceccccsciecs cell} GON GRUSTONS crareteversccielelelevctetcloleletateretaleleretererevererslicicieys eeces aicleleleleloleheloleieleton (Al ee: oR. Dee thas Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure slakal LIST OF ILLUSTRATIONS ML eteseleleve s ciessiciore Sess telel al oe a eieL oe oisiclcayoccs s ai sletalecieleiesinie cee rsiclcee Diplolalorelelalelelalelelelelalcsleveleiers\elslelelele\cialeielolaleials\alelels/le/elsiolelslele/ole2i/; Dielelelelelclclelelercialctelelersiatetel sielolelolelaiels/elelelelele/s\siejeleleisie/eisielaielele(s p50 HMafeteletajetatoteresleleleterevictotelelelolotaieielelelersicletelelaisietinisieieleialcieleiciaiciso) D aresaiors slave versiore aleretskermiomicleteieie sieve isvalen eis eisie oieie sisiniarcieieisiorool Glelelelelaleiele)aleletelcieleleleteievelclelevelelelolelelolelcie/oiclolelsieleisteiolateielalelelerole so, (jarealerareiessic/ oy eletetekeieereperstctensterstalsreisteleleisiore ciciors sieie/elcloloialeicialereltl Giareisveleloseseleleleveleyelereratereiaterereieieleccievsleieleleicicveisiercisielovelsieieyelererarsio nt! D iarelefalsielalelers sleisieloleisinichersteisielelsioislcisisiele steieisiaicicisisicleisiereicieisrere io) AQ et eyoiotelere etstelereielelerolete nterelelersieesletateieversisieteleicrersvolelsicicieieieisieiere tO AA sie ys:e igteievelelaia\eve oiplole fo tereloveretevereqeteie viele Sicfote ers’ eievereicisrelsievelsrers lo 15 55 GOD 0O0000 060000 DODDDDO00OD QUOD OND CONDO DODDO OOOO EO LBB elevelolaleleieiersleleisiele(cleleletolelelelateiieloretersieisieisrieteciericieleisieieterero ne Whe G96 5600060000000000 005000000000 BD DDDDODHaDxOODOODOCES HIG tepavoreia les ovejsieiere;sioim eee revels lelel oie! ele elorstarcieisieie sicietere creiversiee a: ill Gevatelareevototeteverolel efoto sreievelevarnioiatotelofelelsicisielereisisicisieiaieiersiclersiarers Ol SNe Paks retctaice Aceves e\ eis iGo wile nee eavera ein avetavotata ate niara cic aisarelctereiorsis OD Ni VB At 0 AY iv LIST OF TABLES BBs Ille su aiora Sse ose a wrarsra' ce areia ele ercve wieiele cies eleibiere’s alow aiere ec aislach cios'aateold Melole m2 ialelelelalelolelelelelereleletelaloralstotaloleleleieleleleleieleiotclelsiole elelale (ele cleisis\ Pho si ee 1 1 agent (bet roa pa oe aalterined a RR ie a MBE) saadoaed ob av i sit , arene ipa nidiainaie asp Devil a... 2508 ni aie ac ais wae) Bam wa 8 ecto ccna Syleints ld To NNER Baka NaS” eter to Gio low toants ham hngmoe: ote bine mil Lega wh. anntonrt cyano reall waren ge geben Senge At ke ciate a | a ee ieowe ss to RE ino ynlahiie ewe YLLaRoogRe wh asmiaty aciaeaial Wikctad ai Catbondat bwviamb-daved 24 ante amet bes _ labtetas ‘esto to MO Ea weld wiobedyore tare aerw abit ‘Pilenotson +. sco at agatnncnins Soe 8 Ot vpbnks yakbertoa Wendie «3 to cobras ctighb ple sapeademeh’ myowon! edd 26 teste ta Pa OS Ptols| solsiew wheal 7 tet wit $0 omfamttomsy Smad 9 oth eon nesepert Ae eet eat itt ak sore a te Athy ti ptaloy «9 we ante the ares, na Hones th iy wih winbmtiien acts’ dd ‘a ab iad ; £ea3 f£ea3 £eai3 £eI3 £13 £ea3 (penutyuop) yred ge'T O9T‘O 9°T OOT pues out” Ov9E fern 8e'T SST'O 0°2 OOT pues eu 6E9€ yted €e'T O9T"O Vo OOT pues euty BEIE yred 62'T 8eT ‘0 OOT pues eur 9E9E erp €€°T OVL*O OOT pues euy J SE9E yred 87°T SeT ‘0 S*e OOT pues eur VEIE erp G2rU SOT"O OOT pues euty Are, E€9E 41g ie at L8T°O OOT pues euty ZE9E yred O€°T 940°0 S°S Z°9 2° 9° pues 4I TTS 69S€ erp Se°T BETO Wwe | OOT pues eurd B9SE feary (Fak 8eL'0 S°T OOT pues eUuT LOSE erp Beat LL0°0 B°2 itaee Worl pues 44 TTS 99SE Kery ST'T OOT'O 9°% OOT pues eury Are, S9SE kery 6€°T ZOT’O o'% OOT pues eupy Are, VOSE fern OOT pues euty A210, €9SE Leary OOT pues eury Are, TOSE IOTON SUTy.I0g 4ue9 Jeg | 9UeD Jeg] YueD reg UOTLBOTIJESSBTO | oTdureg TTV4LNO YAMS HOVEE LDHOdMAN HL JO VHUV HHL NI SINGWIGHS ¢ GHVL ss it oe 9 A " B La ae wf aah mh a oe Dede 7) mcm eg A pina pedi tn mysbd weur “t SUN tenons > ate mer, HS Ea BA ema epe y : | eis yred Se'T 2L0°O T'9 L*éz keris yr Oe°T 0g0°0 Cul Vaal e°Ot kes3 yareq 6T'T 940°0 Cal Eel keira yreg 6T°T gL0°0 G°€ C'S edb keris yred 6T°T 940 °0 C26 €°L keris yred O€'°T (ora ae) 6°T T’O kesx8 yreq Gea OOT*O oe gL Seis yreq 1G LOT’O Ve BS fes8 yred elie 9LT"0 Ez 3°7 keris yred test T9T"O at Sees | ren wUON Tay | meen ae (an) | JuUeToFFze09 ) seenra unpoTed ee LOTOO SUT ..10g | UeTpan quep seq | 4ueD Jeg (penuTzzU0D) z IVE oOT pues quep zeq | pues pues pues pues pues pues pues pues “4 TTS euty sre, euTy Are, euTy Are, euTy Ate, euTy Are, euty Are, eury Ate, pues euTY pues eutg 607€ BOVE LOVE 907€ GOVE OTE ZOvE ZOvVE TOVE 999€ equ UOTAVOTITSSETO | eTdures 10 The floor of Santa Monica Bay is composed of six bottom material types: rock, gravel, sand, silty sand, sandy silt, and silt. The extent of rock outcrops was determined with a rock dredge which in many lowerings broke off fragments of rock, Pieces of siliceous and non siliceous shale were most frequently recovered, but one large fragment of schist representing a portion of a breccia was also recovered. Bathymetric data indicate that the rock outcrops rise as irregular and scattered mounds. The gravel surrounding the outcrops consists chiefly of coarse sand, well-rounded granules, and pebbles of granite, shale, chert, quartzite, schist, and gneiss. The gravel is relic material formed at a lower stand of sea level during the Pleis- tocene epoch. The overall pattern of the bottom material consists of a normal decrease of particle size away from the coast, modified by the areas of relic gravel and rock and fine grained material in a nearshore portion of Redondo Canyon. Silt-sized grains are most abundant in deep water areas of the bay where wave and current action are slight. The bottom sediments are generally olive-gray color; however, this may vary according to the amount of organic material present. The offshore sand, composed largely of shell fragments, is light olive-gray and is probably being deposited at the present time. Nearshore is detrital sand brought to the bay by streams from the north during the winter and spring. This sand has a more yellow or reddish color than that found offshore. The average median diameter of the sediments in Santa Monica Bay is 0.116 mm and the range is from 0.005 to 1.05 mm. A plot tad etolsg WAT OeAvELS Y Lhe al Dabeod i DEGRYLO Yate tse coy i ak cd seem feet) betta to ‘tort : — dialiaerte He ha Ee TROL angel ip et tesnan hs ero s ei feay Hit ie ca aay bal of median diameters roughly approximates the bottom material chart in showing a general size decrease away from the shore, There are exceptions in both the central area of rock and gravel and the southern area of organic sand where the diameters are large, and the Redondo Canyon area where: they are small. The sediments throughout the entire bay are mostly well-sorted, having an average sorting coefficient of 2.02, although in the canyons and the rock and gravel areas the sorting is relatively poor. Exceptionally good sorting occurs in the nearshore zone where winnowing action by waves carries away the finer particles, and in the nearshore areas where relic sands occur. The organic carbon content of the sediment ranges from 0.13% to 2.76%, with an average value of 0.90%. The sediment immediately offshore, with the exception of the fine material in Redondo Canyon, has an organic carbon content of less than 0.50%, Exceptions to the general offshore increase in organic content occur in the rock and gravel areas where the values are similar to those of the nearshore sediments. The highest values occur in Redondo Canyon and below the shelfbreak. Thus, there is a progressive increase of organic carbon with depth. This may be a result of less agitation of the particles in the water or of greater deposition of organic matter with finer than with coarser sediments, It is interesting to note that there is no particular increase in organic carbon content in the vicinity of the sewer outfall. OCEANOGRAPHY NEAR THE OUTFALL AREAS Salinity Orange County From October 22, 1955 to December 20, 1955, the normal salinity of the main body of the shelf water was 33.45 o/oo (Table 3). The . te euhint peters a dhe gape en int ot nna a ee £0 aoa 1 i aba ies lip aut wiih nari Lormey bas Obxot ash teh a goular it hmniytal iets tbemtbeor erreceraes Se neeeis evi haan & nk “orneht abode ingatttede cul woled ban aS Hal GT Adee, Ebr Kota ataagro Ye ahoreg Ke See post Lal psa popekeeat wt, ec) mote tge someutiott omueing, we hw: nat ead? athe webs an aby, te GP nogeiant o een | re to hat sca oo Des Ls pee ¢ Bhi SANTA , FS) SANTA MONICA BAY ! oO 1 2 3 STATUTE MILES BOTTOM CONTOURS IN FEET 4 MONICA J} VENICE PLAYA DEL REY EL SEGUNDO 455° | HERMOSA dekeal oe "sees | GENERALIZED STREAM | LINES OF FLOW UNDER l TYPICAL | WEATHER Aa | L CONDITIONS ISS | DASHED LINES SHOW OCCASIONAL Noe Vices ala ae, > L: PATTERN . ASSOCIATED WITH. US Giri, Sr e/a Coe 45° THERMAL 4°CONDITIONS 35 1830 2s 24, COLIFORM BACTERIA DISTRIBUTION Field Procedures Dye Patch Experiments Dye patch experiments were used to obtain a direct measure of the rate of disappearance of coliform organisms in the sewage fields. Approximately one pound of fluorescein dissolved in about a gallon of sea water was introduced into the sewage field at the edge of the "boil" above the outfall being investigated. After allowing a few minutes for the dye to become distributed, the zero time sample was taken from within the dyed area. The dyed patch was then followed for three to six hours and samples were removed at intervals, These samples were analyzed for their chlorinity and coliform content. The dye patches behaved differently during various experiments. In some instances the dyed area remained compact and of limited extent; in others, the dye spread out over a large area, usually in ribbon-like form. The dye was renewed as required to enable continuous observation of that part of the sewage field originally marked, In some instances this required about one pound of dye per hour, in others only the initial pound was required for the four to six hour pericd. When samples were removed or dye added an effort was made to pick the most concentrated area of the dye patch. On two occasions colorimetric determinations on samples removed from the dye patches were compared against a standard curve set up with measured amounts of fluorescein, and the results indicated that the concentration of dye in the patch did not exceed one part in 10,000. Lede tenrmggh 4) Reh ho: aed a MENA Seay ea" EAE sel Coen eC Live wi eve "Etod edt Fo ephe | Oe, wie i + an : ews easw eueia ais ts ee ewe t 1 Hara eR RB tinetaoe wrottlon iShetce: os 25 In some experiments, two independent samples were taken from the same patch and analyzed simultaneously; in others, only a single sample was used. When duplicate samples were used, results agreed very closely. All samples were taken with sterile wide mouth bottles, the water being dipped from the sea surface, Immediately after the samples were obtained, the appro- priate dilutions were prepared and the lactose broth tubes for the presumptive test were inoculated. The tubes were placed in the incubator within three hours after inoculation. Surface and Subsurface Sampling The areal distribution of coliforms was examined by taking samples throughout the water column in various patterns around the outfalls, The program of sampling varied with the trip and the location of the outfall. Im some instances, surface and sub- surface samples were collected along the approximate line of sewage flow as determined by the movement of the dye patch. At other times, samples were taken along lines parallel to the coast on both sides of the outfalls, along two lines perpendicular to each other, and along lines repeated morning and afternoon. Surface samples only were collected along a large triangular course in the vicinity of the Orange County outfall. Surface samples were also collected in a close grid pattern covering small areas in the vicinities of the Whites Point and Hyperion outfalls. In all of these instances, collections were made while the ship was underway and the areas involved were covered in short periods of time. The vertical sampling series consisted of a surface sample plus two to four subsurface samples and, on some occasions, a Aiative ont preemie) aE a ein biitpation wat aalquae snare Mild Bag itt _ A ee en ato aS eae PORE NT SIN RO ot ocoriata ite weherol had ange sak iota ben crane - Aer ace = cost slanting. eon ct sos ia sai ae a uh. ine oaw: nate sera wt enact to ree at MLE EN: HON UO De 26 sediment sample. The surface samples were taken with sterile bottles as were the dye patch samples. The subsurface samples were collected with sterile bacteriological samplers (Fig. 2). Water for various chemical determinations was collected at most profile stations; the hydrological and bacteriological casts being interspersed. In all instances, the appropriate dilutions were prepared and the lactose tubes were inoculated and incubated within an hour of obtaining the water samples. Sediment Sampling Sediment samples were taken with either a corer or a snapper; the latter being used most frequently because the coarse texture of the sediments near the outfalls made coring difficult or impossible. Immediately after retrieving the sample, a measured portion was suspended fn sterile diluent and coliform counts were made on the resulting suspensions. An effort was made to sample only the surface layer of the sediment. Laboratory Procedures Determinations of Most Probable Numbers (MPN) of Coliforms Standard methods were followed in all details for the determination of MPN. Lactose broth and E.M.B. agar respectively were used as the presumptive and confirming media. In general, all positive presumptive tubes in the three highest dilutions showing positives were confirmed. All negative confirmed tests were completed. Six dilutions to 107? were prepared from almost all of the water samples examined and consequently most tests were determinate. Four dilutions, 1071 to 10-4, were used for Meigs Vey “ely wot aGtadeh Se a pevoos om moe Peabaese _ Ubetiveiner cay MM Bele bond mrtont AOL No sotanbirsede i re eo OR HEEB aruda Figure 2 Bacteriological water sampling device. Cath ‘ mn rotew Teotgol, Sakti ' eae, Mat 28 most sediment samples. Five lactose broth tubes were used for each dilution in the dye patch experients and two tubes per dilution were used for other types of samples. Identification of Coliforms For conclusive identification of coliforms, typical colonies were picked at random from positive confirmed plates and checked morphologically and biochemically by Gram-staining and by the Imvic tests. Several dozen colonies thus check proved to be species of either Escherichia or Aerobacter, Enteric Pathogens An effort was made on two occasions to isolate enteric pathogens from the sediments around the Hyperion outfall. About one gram of mud was introduced into tetrathionate broth and the cultures incubated at 37°C for 24 hours. These enrich- ment cultures were then streaked on S.S. agar plates. Suspicious colonies appearing on these plates were transferred to triple sugar iron medium. Tests’were not continued beyond this stage because all colonies examined proved negative for pathogens. Disappearance of Coliforms With Time (Dye Patch Experiments) A total of sixteen dye patch experiments were conducted; twelve at the Orange County outfall, three at Whites Point, and one at Hyperion. Of the sixteen experiments, thirteen showed a marked and usually consistent disappearance of coliforms with time. These will be discussed as a group. The three "atypical" experiments will be dealt. with separately. dabetele | at ( 7 , WE Sle 37 Figure 5 The horizontal distribution of the sewage field in the waters surrounding the Orange County sewer outfall on December 19 and 20, 1955. BE ir icO Ta aaa hae ALINIDIA GNY AVE LYOPANZ : | sesh GG, Calla! 2 O)\/ihalS 1744 NI SYNOLNOD ‘94d 0006 SATIN aLNivis Abel e}<) stititititit Oc ee 6l HOV3G NOLONILNOH fe) OOOE Pees ae or | eee ees 19S 18S 100 II izoll® Ne << 89° BEC ae > HET ore. Diese SA RSE GE we f i = ingise sive 38 direction, gives the "best fit" curve shown in Figure 6. This curve shows a decrease in coliforms to about ten per ml in a distance of 6,000 feet from the outfall. Of the 35 samples taken from the VELERO IV at greater distances from the point of sewage discharge, none gave counts of over 10 per ml. An inspection of Figure 3 shows that the average coliform counts in the dye patch experiments decreased to about 10 per ml in roughly six hours. If one assumes that the sewage field is moving at the rate of 1,000 feet an hour (0.2 knot}, a value that roughly corresponds to the observed rate of movement of the dye patches, then there is a good correspondence between the dye patch data and the surface sample data. Plotting the dye patch data on the basis of this assumption gives a curve (Fig. 6) that is somewhat higher than the surface distribution curve. Since the surface distribution curve is based on some points that were probably not in the main sewage field, one would expect it to show a more rapid decrease than that found along the main direction of sewage flow as measured by the dye patches. No attempt was made to map the surface field arowd either the Whites Point or Hyperion outfalls, but surface samples were taken with the vertical profiles in these areas. The data show a decreased count with distance, although the results were more variable than at Orange County and the rate of decrease was not as rapid. Thus, counts greater than 2,000 per ml were found 9,000 feet away from the Hyperion outfall and counts of greater than 200 per ml were observed 12,000 feet from the Whites Point out- fall. In the area of the latter outfall, visible patches of greasy slicks were observed on the sea surface as much as four ey nt beer so One’ nate 4.0) “3d 9 oot se a ee Ba cm oe Si | _ beeros! jae a Ba wee = i bits ae aia» ont — bina dat ae aes pe)” | sma ah ay tl | i. an ee st so pita pnts ot | oaw ei apatue ela 1G i an wom’ 2 0) agp es Bab RAO tone vattanie: he Hoey $06 wr) eee sete helena et ae poe ikea ho tired | fyi hn mane a dP er athe ey CO CRN aa fan: oN gi ; a aire Me) pero ene mihin ty Liketstee ed aa ss alos nsoh an Seas ee coed ae “gis 39 Figure 6 Coliform count versus distance from the outfall plotted with average coliform counts in dye patch experiments. Orange County sewer outfall, December 19 and 20, 1955. S emg wos mrotheod [— LJ Li Lo = =| =) 6 Lo |-— =) O = O fag L LJ UO Zz < - ”) O ie ah 7 atl i )0 or five miles from the outfall. These slicks apparently do not disperse nor break up rapidly and the occurrence of high comts at great distances from the point of sewage discharge may relate to their presence. That coliforms are not uniformly distributed in the surface waters even within the main sewage field is clearly seen from the results of three experiments in which surface samples were collected over a small area within the main sewage field. The first of these experiments was run at Whites Point were a grid of 23 samples covered a square about 1,000 feet on a side located roughly 1,000 feet up coast from the outer Whites Point boil. The position of the grid overlapped the path of travel of a dye patch started at the inner boil some five hours previously. The location of the grid is shown in Figure 7; the counts obtained on the grid samples are the basis of the contours also shown in Figure 7. From the extreme variation in the counts observed (Fig. 7 and Fig. 12), one might conclude that the boat was passing in and out of the sewage field during the collection of the samples. However, calculations based on the chlorinities of the samples showed that the per cent sewage varied only 2% fold, from 0.6% to 1.02%, making this argument invalid. From the per cent sewage and the MPN of the samples, the original of "100% sewage count™ can be calculated (Table 8). It can be seen that the highest "100% counts" are within the range of what might be expected for an unchlorinated primary effluent, suggesting that no mechanisms are at work that might tend to concentrate coliforms as compared to the liquid phase of sewagee On the other hand, the low "100% counts", and there are alt vi : BORIo enetaw aed ads)’ DH i at, due reLieteg » Ta Figure 7 Location of Whites Point grid ad the distribution of surface coliforms within the grid. eit aod Gr DETAILS OF GRID SHOWN AT LEFT MPN/ML o >5S000 FEBRUARY 3, 1956 1000-5000 500-1000 100-500 50-100 Ke 2 O a ”) Lu ies it = kK a Le O Za O KE =) c a K- wo a be ve DELYITS Shee SH OMM ae 2 @) —— oooe.” Gy Wah ds & CALCULATED "100% SEWAGE COUNTS" FROM WHITES POINT GRID SAMPLES (MPN/ML) Per Cent Sewage TABLE 8 Observed Count 1,300 6,200 2,300 )2 Calculated 100% Count 81 96 29900 50,000 900,000 99,000 1,100,000 3,0 ,000 73,000 ) ,000 100 600 6,500 31,000 250,000 150,000 73,000 9,000 700 250,000 900,000 100,000 43 many of them, are far below a reasonable value for a primary effluent. These low values show that coliforms disappear much faster than the liquid sewage phase and reinforce the conclusion from the dye patch experiments that factors other than dilution play a major role in coliform disappearance. The median count for the 23 samples is 73,000 per ml. If one accepts the maximum "100% counts" (1,000,000 per ml) as the average of the plant effluent, then one can conclude that about 93% of the initial coliform population had disappeared for causes other than dilution in the time (or distance) of travel from the outfall to the area of the grid. On the other hand, one must also conclude that individual patches of sewage will show essentially no reduction in counts beyond dilution over the same path of travel. Two similar grids were run in the vicinity of the Hyperion outfall on March 8, 1956. The grids were located between two dye patches started almost simultaneously on opposite poles of the boil and were rectangular in shape, being about 1,000 by 2,000 feet on the sides (Fig. 8}. The first was about 1.6 hours travel from the outfall, the second about ) hours (Fig. 9). Al- though the range of counts in these two grids was about as great as that observed at Whites Point (210/ml to 70,000/ml for grid one; 62/m1 to greater than 70,000/ml for grid two), there was a much more uniform distribution of coliforms (Fig. 9). This is also shown in Figure 10 in which the per cent of the total samples giving a particular count is plotted against the log of the count. Almost 50% of the counts in the first grid were the same and a large share of the other values represent differences Ban adie 00, ss a id le ewig taumbbvesat tats seutonoo oe 4 Sra tt cere thy Ny SRE hy ei pasted oak o hot cess oat 4{8: ie asbia: ‘wild 3 bod ‘tek og Ks noan bacon ett caer ar wot te va at ‘ TRS bE - aay ieee ad pao) Sabot os Et pecan Hous Sha eTeNy Sah it Nici aa ies sa sabe ae aba “Bh Oath i RR eoianse Leos’ sae the tha aug cla matt ot a cl te. pot Belt deudage bonvate 8 i Sy 3 | ote, anew bie 232) i wild, Figure 8 Locations of Hyperion grids on March 9, 1956. ihe aee 9S6| 6 HOYVW — W1VW4LNO NOI3SdAH NOILNGIYLSIG WYOsITOD JOWalsVs =SatD sO NOL oo7 /SC ell o) L5 Figure 9 Surface coliform distribution on grids near Hyperion outfall on March 9, 19566 ti | repr runt ae it Dh the eg, lOO — 500 lOOO — 5000 5000!— ||O01I00 |O.O00—50,000 BS 1 F, SSO 9 OKO SSS SS WN WSS = SOYOOO CIS QZ I956 MARCH 9, OO eo ee eS Ae Coe KO RS SO Se a aS LAL F C) O S cL —) 07) i et ea amy yr ee Los ivr vidal Melt 7 of only a single positive tube in the presumptive tests. The results of the second grid were a little more variable than the first, but here also, over 60% of the counts were concentrated within a narrow range. There is no evidence of any significant loss of coliforms from the sewage field in the time elapsed between the two grid samplings near Hyperion. Actually the average MPN for the second grid, 11,500, was somewhat higher than the average for the first grid, 7,100; more significantly, the median values were 2,300 for the first and ),300 for the second, and the geometric averages were 3,100 and 3,300 respectively. However, there was a considerable reduction in count between the samples taken in the boil and those from the grid 1.6 hours later. A comparison of the data from the two grids with that of the earlier dye patch experiment shows that similar couts were obtained at O and 2 hours, but that the counts continued to decrease in the dye patch whereas the grids showed no further decrease over the next two hours. Of the 50 four-hour grid samples run, five (10%) had MPN lower than the dye patch sample at corresponding time and 11 (22%) had just slightly higher MPN. Thus, the data from the dye patch experiment, although not neces- sarily reflecting the average behavior of the sewage field, was certainly typical of part of the sewage field. Subsurface Distribution of Coliforms Approximately 30 vertical stations were occupied during four trips to the Orange County area; 30 stations on two days at Whites Point and 20 on two days at Hyperion. Typical results are shown aoa ‘aymop A ap. solizee ns oe Bentagdo, x Daa bt ‘ont Sw I eta fs 48 in Figures ll, 12, and 13. Considering the vast volume of water being sampled in these series and the very small numbers of samples that could be taken, it is certain that the profiles presented can- not be considered as an exact representation of the subsurface distribution of coliforms. Nevertheless, certain features of the profiles appear repeatedly in the various series and suggest two general conclusions. The first of these is that the highest subsurface counts occur along the general lines of surface movement of the sewage field. For example, Figure 11 shows two profiles obtained on the morning and afternoon of the same day. In the morning, the surface sewage field was moving upcoast, while the direction was reversed in the afternoon. It can be seen that the subsurface MPN reflect this altered movement. The Whites Point profile of November 3 and the Hyperion profile of January 12 show the same effect; high subsurface counts in the direction of surface movement, and essentially zero counts in the opposite direction. Such a pattern could result in at least two ways; either by assuming a uniform direction of move- ment of the water at all levels with subsurface as well as surface sewage flow, or else by assuming all sewage rises and flows at the surface only and subsurface coliforms represent sedimentation from the surface field. The repeated occurrence of tongues of high coliform cout extending downward from the surface provide evidence for sedi- mentation as the major factor determining subsurface coliform distribution. Such a tongue is clearly seen in the profiles in Figure 11, 12, and less prominently in Figure 13. It is quite clear in Figure 1h, which presents an average of all the profile BOR By RVR wotney ik “ibetawere: tasqqe sal Pion ‘elem Larne EF pevee at a cae ee iS Wea. F y i ny ee wey res eee BESIEROS 0) 2 L. be 5 3 6 +4 a wh. - PL y= @ AA i ai 4 2 to Noorredea bas” Ypilvon shy biskt a oy ' \ ee ee oe ae He _ YY avo hexradia i mn Cai i f etary 9 Figure 11 Typical bacteria and temperature profiles extending parallel to shore in the waters surrounding the Orange County sewer outfall on December 19 and 20, 1955. fattexaa prtbes oR: a ASLBors ini otidaremsd bee 9 atxetand Le ot : 7 bis Ehsxta ene ih pynew Wid gutdworim onedew coil me 140002 OO! > INS <= 00S-OO| WY OOOI-00S 000S-000! 000‘0!1-000S 140002 000'0S-000'O! 000‘'0S < 14 0002 Oool TAEUMO O TIVILNO < Q OOol 0002 3 A] a relist eeaneneeec ne WahyelLEinye© 0002 2 < = < kale] @ Z 7 mm [7] = Nevin Se By ales tty NR Fath Aen er i Maret ha Ht 50 Figure 12 Bacteria profiles extending parallel to shore in the waters surrounding the Whites Point sewer outfall on November 3, 1955 and February 12, 1956. ae sot litw ksh gig % JLINNOcl —SSiellAlMA ILM IW /Ndn SWYO sl 109 A an So re e, 65 <> SOY 5% % "ee SS > e o % 52 CxS SRS > OX? KO 0% 550 TAINAN SS6| YAEGWAAON € RS WH sees use \ 3 3 W Os=ol 2 OOS —OS SS $S KOCK] Li OO00'S —O0SG oC00';0dZ < AW /NdW KEKKK Waele kW HiT a MT . ' ’ rT ior nei) oi He Pita tal Aiur le wpppredretipete ew 51 Figure 13 Bacterial profile extending parallel to shore in the waters surrounding the Hyperion sewer outfall on January 12 and 13, 1956. “6. pig: of LS erecy se) wt we af sgeabas 4 : 7 NOlial Slaelal sL)y/ TW/NdW SWYO Al 10D 00001 < OO0O0OI-O00S 000S-000! OO00I-00S 00S-00I OOI-OS qW/NdW 9S6I NVP El NS OC Mm 1) = ae Lysis} NII 0002 OOo! 0 s002~«SO00E L354 NI T1IV4SLNO WOU Ss SONVLSIG bar aan ae Nok weal DRS ene iy pou esta £ NERY yi) o i we Br, lesen teas rer gona vee tne ieee a supe He ; ia 52 Figure 1) Vertical distribution of coliforms independent of direction in the waters surrounding the Orange County sewer outfall on December 19 and 20, 1955. i a =a ihre Fee “7 phere ot. a to mo bsani bata faonset ie ee ero VOD syneTs ef yA ue At Oool> 00S-OOl| SS 0001-005 feee4 000S-0001 § 000‘0I-000¢ |: 000'0S-000'0 0000s < 0009 OOOS OO0OV Jbz\els|~ (Nil ox \ 0002 TIWALNO WOYS ADNVLSIC H1d 390 Za mn m m —| phA ili WAT ap: ' aud Wee a Wel sae) Dey eat Agree Ahi th 53 data from Orange County, in which the MPN are shown against distance and depth, but independent of direction. The tongues cannot represent a subsurface flow of sewage away from the outfall for several reasons. The most compelling of these is that the temperature and chlorinity of the water in the tongues are characteristic of the normal sea water in the area rather than being characteristic of the surface sewage-sea water mixtures that have similar coliform populations. Even if the profiles are greatly distorted because of insufficient data, the finding of even individual high subsurface counts in areas of normal chlorinity can only be explained by assuming that the liquid and solid phases of sewage move differently after being discharged into the ocean. The main, if not only, differential force acting on the two phases is that of gravity and the high subsurface counts are almost certainly due to sedimentation of particulate material. Although most of the profile results can be explained in this fashion, the results obtained on February 12 at Whites Point remains a mystery. On this occasion the pattern was confused with alternating highs and lows, with the highest count of all being found some 12,000 feet up coast from the boil at a depth of 65 feet. Coliforms in Bottom Sediments In the First Quarterly Report, mention was made of the detection of coliform bacteria in the sediments over a large area surrounding the Hyperion outfall. At that time it was the authors! understanding that there had been no large scale introduction of coliforms into the area for a period of over a year, and the question arose as to whether the organisms found were indeed coliforms and .- oF auth yintsdxeo “ome on ~~ oon bEireToe | Teg wt iy eddies: el rtow sity te: seem uot a a4 owns te ge Pasiriiel ‘tn, boakssta ettover arly riot — ‘mime wroteey atid perros etds “oO serodeym a seorighd adi: dtu geieo. tak ght wheat Sto cidses a ca Tee oats wert dusoo ar font” > thuseaen morton a ee oe “te ‘in May nobtbon (drow ia awit ‘add’ nt ‘Lo vtom inet 0d guahempeat aie eal ont Aaa 5h if so, whether they represented survivors of those introduced a considerable time ago. As a consequence, their occurrence in the Hyperion area was reinvestigated and exploratory work was done in the vicinity of the Whites Point and Orange County outfalls. Some 70 samples were collected in Santa Monica Bay covering essentially the same area previously investigated. The area in which positive samples were found in either the present or previous survey is outlined in Figure 15. In general, the extent of the field appeared about the same on both surveys and the numbers of coliforms found in the sediment samples were similar. All typical colonies picked from positive confirmed plates proved to be coli- forms by the Imvic test and morphological examination. All tetrathionate enrichment broths set up for the detection of enteric pathogens proved negative. The counts made on sediments collected in the vicinity of Whites Point and Orange County outfalls have been quite variable. Samples from essentially the same location have shown high counts on one occasion and low counts on another. In a series of four cores taken one after the other near the Whites Point outfall making every effort to sample the same location, surface counts of nil, 6, 23, and 23/gram wet weight were obtained. This range is not excessive and coincides with the range given by three separate samples taken from one of the same cores. On the other hand, two samples taken near the Orange County boil gave counts of nil on one occasion and of 10,000/gram on the other. The sampling procedures used for the sediments are now believed to be grossly inadequate for the following reasons. It can be assumed that the majority of the coliforms occur in a %6 agin dod mi aihesh ore terete besoogna bls ub Aaa ‘ot an k | seen entbe beni loon evidiaog mol betke.L ‘i ae teva 586. i 7! piotkerres bes. te +9 sewnih eit vd porto obsiia 0 ot ene eile 4A ou ten addond dnamtotine svenolittentad ; “i ; . . y , 3 : 2 sv ies ie Oey pate modteg SY Oe Ee He ae) ive BIGIOD poy iota even motdeecl enw it yale lonesge:; si Cini i i = te : , \ pe ORK Rh, PeteiGH oan ocatow . mes Ce, BGR ts “2 attn to ; ‘ 5 A = SEMTEY UC A REA Tard w 2eblonied fis ovis aeuxe dom of 55 Figure 15 Distribution of coliform bacteria in the bottom sediments in the vicinity of the Hyperion outfall. Mi ilk ah y Ye y oth Lon. Mee J a 1 aut v re ha Mien 1 Ale tit a aiiiins rm 5 OO SERS SHOR MOSK S505 ‘30 O€ yea] - | ‘AON O€ KR IES 6 SS ‘ONV 11-6 AAILISOd e SAILVDAN © SSW ALNivis € 2 1 0) JUINSINIGEIS — WO LALOxE) INI VWhels Lowel “WihkelOall 1O2 WS YOINON YWLNYS bs i ee: : : Gf qu i i. ie a 56 very thin layer or film at the sediment surface which should be fairly fluid and mobile. ‘When samples are taken with a snapper, it is probable that this layer is disturbed both during the actual collection and also by the washing received during retrieving the snapper through the water colum. When samples are taken with a corer, this surface layer usually remains intact until the core is removed from the barrel at which time considerable distortion can occur. In either case, when the sample is taken for analysis, variable proportions of the surface and subsurface layers are included and results will not be comparable nor will they express the maximum surface populations. For the future program dealing with this problem, a new type of sampler has been devised that captures the entire surface layer of a given area of sediment. If the total sample is then used for preparing the required dilutions, one would determine the coliforms per wnit surface area which is the key parameter in this problem. Because of the sampling difficulties, it is believed that the counts obtained in the various sediments are minimum counts and that much higher populations may occur in a thin surface layer. Whatever the quantitative difficulties inherent in the data, there is no doubt that the organisms detected are true coliforms of sewage origin and not peculiar marine bacteria that happen to give positive confirmed tests. Whether the detected coliforms have survived in the sediments for long periods of time or whether, alternatively, they are of recent deposition cannot be decided. There are certainly enough coliforms in the solids settling from the Whites Point and Orange County outfalls to account for the observed sediment population in those localitiese iH i} ui at bas reine vee ‘won 7 nee 10% eye: ne be i tet at it, : i 1 y Hy i jiobeteme 2) niseehsiennl nl sda nieve 4 aml sh andl veld ‘avid a joey iter = ws ai 57 The same is probably true around the Hyperion outfall since the data now available on the chlorinated effluent routinely discharged indicate large coliform populations may survive the chlorination. It is reassuring, however, that none of the 70 samples tested were at all suspicious of enteric pathogens. Fate of Coliforms Considering only the data presented so far, the interpretation of the results appears straightforward. It has been shown at all three outfalls that the effect of dilution on reducing the coliform count is very slow after the initial mixing of the effluent with sea water in the immediate vicinity of the outfalls. Initial dilutions of the sewage as low as one part in 35 at the surface have been calculated from chlorinity data at Whites Point where diffusers are used, and indications are that most of the sewage reaches the surface without appreciably greater mixing. It appears safe to conclude that a similar situation would exist at the proposed outfall, that the entire volume of water in the bay would not be available for mixing, and that dilution by itself would not reduce the coliform population to a point where State standards are met. It has been demonstrated that at all three outfalls, factors other than dilution cause a significant disappearance of coliforms from the surface waters. One of these factors has been clearly shown to be the process of sedimentation. It is our qualitative impression that no other factors beside dilution and sedimentation are of significance in the disappearance of coliforms over the initial six hour period after discharge of the effluent. Unfor- ce aks ote ES ek asi atte Ce GP | eo) ee CP Tn Pay ek a + one a6 se 1 nal & aut “buona sae . Pat, shure Panty ois in tadt Bed otanonn b ved atl at a oft ToT ES) St ait ‘atest 58 tunately, because of the highly variable composition of the sewage effluents and the impossibility of analyzing a sufficient number of subsurface samples to give an exact quantitative picture, one cannot calculate whether the extra disappearance of coliforms above dilution is due entirely to the sedimentation process or whether death and other factors also play a significant role. In this connection, beach count data around the Hyperion outfall clearly indicate survival of coliforms for greater than 2); hours. For purposes of prediction, however, the causes of disappearance are secondary as long as the rate of disappearance can be estimated. The rate of disappearance for all causes in the vicinity of the Orange County Outfall is such that counts of more than 10 coli- forms per ml should not occur at distances of greater than six hours travel from the outfall. The surface distribution of coli- forms at Orange County and the observed rate of travel of the dye patches, as well as other data, indicate that currents of 0.2 knot or less are typical for the area, giving a pollution boundary of 10 coliforms per ml at roughly 6,000 feet from the outfall. Since the dominant direction of sewage flow observed in this area has in general been parallel to the beach rather than towards the beach, little pollution would be predicted for the beaches in the vicinity of the Orange County outfall and what does occur would be expected within roughly a mile on either side. Actually, the beach count data available do not bear out these predictions. The possible reasons for this discrepancy will be discussed in the following section. If the rate of disappearance of coliforms in the Orange County area also held for the proposed outfall in Santa Monica Bay, then hy, fink oeue> {0 202 vavomencaty to ate tf cients peedt eteotbat Qmyeb re De om ee Bo a qithvts ,peh edgy oe i Seahh aot bet othoamp of bloow anise cose ie sot deri Bee Lietdae. i 0 goa ht Latte Weddhe ie atin s phere co wisps alent ‘sao ton! lea 59 one would predict from the oceanographic data available, that there would be an ample margin of safety against beach pollution. The extra volume of sewage to be discharged increases the coliform load by roughly one and one half magnitudes. Since the overall disappearance curve is exponential rather than arithmetic in character, the extra load would mean an increase of only about two hours for the counts to fall below the 10 per ml level, all other factors being equal. The dye patch data suggest that the rate of disappearance is not the same at the three outfalls, although the rates did not differ markedly between Orange County and Hyperion. If the disappearance curves for Hyperion and Whites Point in Figure 3 are extrapolated, they intersect the 10 per ml level at about 7 hours and 10 hours, respectively. Since the curves are based on single runs, these exact times cannot be taken too seriously. However, the slower disappearance of coliforms in these two areas, in the order given is also supported by the surface distribution, including the data from the two grids run at Hyperion. The "viability" studies done by the Los Angeles Sanitation District indicate a much slower dis- appearance around the Hyperion outfall as compared to either the rate we calculate from our dye patch experiment or to the rate around the Orange County outfall. The questions as to which rate should be used for estimating the situation that wuld exist around the pro- posed new outfall is discussed later. Orange County Beach Count Data The beach data in the vicinity of the Orange County outfall shows that coliform counts (from the Orange County Sanitation District) in excess of ten per ml occur fairly frequently and 60 that on occasion the State standard of not over ten per ml in 20 per cent of the samples is exceeded. ‘he area of excess counts extends from about 3,000 feet down coast to 15,000 feet up coast from the outfall. If the morning and afternoon samples are con- sidered separately, the picture differs somewhat in that the polluted area is more restricted in the afternoon and extends farther upcoast in the morning (Fig. 16). Contrary to what one would expect from the coliform distri- bution observed in the ocean, the area of excessive counts did not show a peak within the beach zone less than 6,000 feet from the outfall. This is particularly surprising because on at least one occasion a dye patch experiment showed that the sewage field could reach the surf zone in a period of three hours. The occurrence of excessive coliforms on the beach over 15,000 feet away from the outfall is also incompatible with the coclusion that the coliform field does not extend for more than 6,000 feet from the outfall. Assuming that the dye patch and profile experiments give a representative picture of the coliform field in the ocean on the days of the experiments, and there is no reason to believe other- wise, several explanations may be offered for the discrepancies between the beach and ocean distribution. First, and least probable, is that the observed beach counts are due to "bootleg" sewage introduced at points upcoast from the outfall. A check of the area failed to show any source of sewage of sufficient magnitude to be responsible. The second possibility is that high beach counts occur only on days when unusual conditions exist. If, for example, currents 61 Figure 16 Beach counts along the Orange County coast exceeding 10/ml from August through November, 1955. pitts: So ony volt Hones Jerod’ id NOl NEI 62 of a half knot velocity or more occur periodically, the sewage field could be carried 15,000 feet in six hours and thus bring excessive coliforms into the beach areas as observede This supposition could be checked if there were some pattern from which times of excess counts could be predicted. Unfortunately, no such basis exists, and it would probably be necessary to make many trips of the type already carried out until one, by coincidence, happened to coincide with a day of excessive beach counts. An alternate possibility of the unusual conditions hypothesis is that the character of the sewage effluent alters in sedimentation characteristics from time to time so that the extra disappearance of coliforms over and above dilution is retarded or eliminated. It is obvious that the longer the suspended solids remain on the surface, the farther the sewage field can extend. The authors do not have sufficient knowledge of the characteristics and variations in the Orange County sewage to know whether this alternative has any validity. A third possibility is that the high beach counts are correlated with periods of excess plankton in the inshore waters. There is some evidence in the literature that coliforms may be associated, mechanically or otherwise, with plankton and thus be more widely distributed as the plankton are transported through the water. At the moment, there is little relation evident between the available plankton data and the beach counts. Fourthly, it is possible that the coliforms, once reaching the surf zone, are carried upcoast by a longshore drift. This idea is based on the supposition that sedimentation is a major factor in the disappearance of coliforms and that die-off is a minor one nae Bias j oa Sg wi ron sionbok ven wen ota mired 4a gitar foe oe ie te LRM 63 over short periods of time. It can be assumed that once the suspended matter reaches the surf zone no further sedimentation will occur. Consequently, coliforms brought into the surf would then disappear only by dilution of slow die-off. With an upcoast drift, material brought into the beach less than 6,000 feet away from the outfall could be transported greater distances away. How rapidly coliforms would disappear would then depend on dilution and whether a diminution from this factor or others occurs is not known. It would appear that an investigation of the fate of coliforms in the surf zone is a necessary step in understanding the situation at Orange County. Finally, it may be that the coliform counts on the beach are not directly related to the sewage being discharged, but instead are determined by the distribution of coliforms in the bottom sediments. It is conceivable, from the scattered data obtained, that the bottom has a high coliform content for a large area surrounding the outfall. If this field of coliforms extends in- shore for a sufficient distance, it is possible that any oceano- graphic condition that stirs up the bottom will result in a fresh introduction of coliforms into the water along the beach. One would expect from this hypothesis that a correlation should exist between beach comts and local wave action. More complete infor- mation is required on the extent of the bottom coliform field before this possibility can be properly evaluated. In summary, although the beach count data do not correlate exactly with the predictions from the dye patch experiments, the discrepancies can be explained without discarding the observed rate of disappearance as being typical for the average conditions around the outfall. owed es ohne Leeman, ie i dai . Te NAR toasted “eit ob atte witt pinthearon sen fai 3 tae ¢ ‘ , osvar ke Pngiertiin a 0%, : exit ‘ 7 v ) yet aNd ade vant or, a tide) 4 CRU 6, Los Angeles Sanitation District Data The personnel of the Los Angeles Sanitation District have been conducting "viability" studies on coliforms discharged at periodic intervals in the unchlorinated secondary effluent of the Hyperion Plant. Their data are interpretated as showing a much slower rate of disappearance of coliforms than was observed in the dye patch experiments of the Hancock Foundation. Figure 17 is based on a composite of the data of the LASD experiments and indicates that roughly a 6.5 hour period is required to give a 90% reduction of the initial boil count and a 2); hour period to reduce the count to the 10 per ml level. As is described below, the field techniques they used in their experiments differ from those we employed. Since their rate of disappearance differs so markedly from ours, several questions arise. First, are the differences in methods employed responsible for the differences in results? If so, which method is superior for estimating dis- appearance rates and which, if any, should be the basis of pre- dicting the situation around the proposed outfall? These questions will be dealt with in turn. As already described, in our dye patch experiments a single point at the edge of the boil is marked with dye. Samples are periodically removed from the dyed area, and dye is renewed as required to follow the marked field. An effort is made to choose all samples from the most intensely dyed area of the patch and to renew the dye in this area. In the Hyperion experiments, the sewage field is marked with one or more dye patches as well as with current crosses. For each point on their disappearance ices ne pe ‘xe. davon! Liked pes ‘pte sie cobtoubet ROR” wh sa Bh. ohare a bie: ae Beale on | = a Wa ie ON 7 = yet socethh fh LE bord ae oka ws ot Semen Cs ‘ 65 Figure 17 Average reduction of coliform densities in Santa Monica Bay. (Graph based on data obtained by the Ios Angeles Sanitation Dis- trict). "bo peaks other ouerowl. wy Hy panded twe wetmand col ad? ra Renteddo adab no hewed agent 8 16 20 ELAPSED TIME — IN HOURS AVERAGE REDUCTION OF COLIFORM DENSITIES IN SANTA MONICA BAY (BASED ON DATA OBTAINED BY LASD) 66 curve a traverse is made across the area defined by their markers. From 2 to 10 samples are taken on these traverses which in some instances extend over several thousand feet. The maximum count obtained on the traverse is interpreted as marking the "center" of the sewage field and decreasing counts are interpreted as meaning departure to varying degrees from the main field. The line shown in Figure 17 is an approximate "best fit" drawn through the medians of their disappearance values at the various times of sampling and is interpreted as representing the average picture. Apart from the differences in the nature of the experiments, there are no apparent differences in the techniques employed for determining coliforms that would account for the differences in results. Dr. Mittwer has observed the LASD techniques and Mr. Garber has observed those of the Hancock Foundation. Both are satisfied that the techngiues are essentially similar. Personnel of the AHF have usually employed five tubes per dilution in the dye patch experiments whereas the LASD have employed two tubes. Although this might make our individual determinations a little more accurate, it should not affect the general findings. We have always taken our samples from the dyed area while many of theirs were taken from areas there no dye was present. The possibility that the dye used might be toxic to coliforms was considered, but laboratory experiments failed to show any toxicity whatsoever at concentrations much higher than those present in the dye patch. The grids run at Whites Point and at Hyperion show that large variations in coliform counts are observed in samples taken almost simultaneously over a small area of ocean surface. It was pointed A cyiive'y fees th paint Rey, aks : Final ; Bate hi Veg ts ey a ee ee) ae V3) STRELA Ch i te x ier ot 67 out that the variations in sewage content of the Whites Point grid were very small and the variable counts cannot be ascribed to passing in and out of the sewage field. The same is apparently true in the Hyperion area. At the same time the grids were being run, the Hyperion personnel were measuring "viability" according to the described procedure. Their two hour traverse had three points within the area of the first grid, and their ).7 hour traverse had four points within the grid area. The counts for these seven determinations are shown in Table 9, along with other pertinent data. It can be seen that the variations in count can- not be ascribed to variations in sewage content. It also can be seen that traverse A and B taken by themselves indicate a marked reduction in count over the period involved, but that the results from the grid over essentially the same period do not indicate this decrease. If one takes the zero time count on the same day and the two traverse averages, a marked decrease is observed that approximates the results of our dye patch experiments, i.e., O hours - over 70,000/ml, 2.0 hours - 22,000/ml, and ).7 hours - 3,000/ml. Thus, data can be chosen from their runs that gives a picture almost identical to ours. The conclusion from this discussion is that both methods are measuring the same thing; that is, the disappearance of coliforms in the individual patches of the sewage field that happened to be sampled. Neither is presenting a picture of what happens in a representative sample. Either will determine what should happen on the average, and both should give essentially similar results if equal numbers of samples are examined by both methods. These conclusions are reinforced by the data obtained when LASD personnel ae iy bi ie hpi hatha ¥ ) RY) ta: neee od 6G } at enabte iar Hom: ‘phe okaaa A heey “Hold pene | Sf hee si } mm Moby °| ee ae pain i ta.td need rena? ond 3E.. gained, exp eoyatars ‘awrovsad owt ert bam 7 » i e wupid: Nea rv ae SMELT tye Suton awh Yio be adLennint wile aoddukeingge, “ta ii ne mas ‘ , iy Aes, re CO om orca ei, gli OOO, OF reais a oan St Leah, sua Ae abn q ane a o HD. atah ,hote i ute! Ae Ue Math tes bt nro od Knotdneatst yh Piet a.elw meet mtb Ree ey Oe Ra ert a a 3 4 es Dore diya atya pduad beara: tele SRL Lhe wail LE eign «9 ed) ety at 1 | woth Runes bet Bs af, ar ke Puy aha. ERO, TABLE 9 A COMPARISON OF DATA FROM TRAVERSES CROSSING TWO GRIDS WITH THE GRID DATA Station Traverse A =- 11251 11:52 11:53 Geometric Av. Traverse B =- 1:29 230 331 332 Geometric Av. Grid #1 ey 112)0 Geometric Av. Grid #2 13259 1:12 Geometric Av. Calculated MPN CL o/oo | % Sewage 2.9% 3.5% 5.0% 2.6% 2.8% 2.2% 5% to 3,100 to | 68 Bo ee oa te Se by 69 used their procedure in the vicinity of the Orange County outfall. Their results were identical with those of the AHF. Since they have run many experiments around the Hyperion outfall and we have run only one, it is probably that their results give a better average picture than ours. The question then remains as to whether their disappearance time should be used as a basis for predicting the situation around the proposed outfall, and the answer to this is probably no. It can be taken as established that the disappearance curves around the three outfalls differ. The cause of the difference is apparently not the differences in volume of sewage being discharged at the three outfalls; for if this were the case, one would expect the order of disappearance to be Orange County, Whites Point, and Hyperion. Nor is it the difference between primary and secondary treatment, since then one would expect Whites Point and Orange County effluents to give similar results. If it were a question of a difference in outfall construction, diffusers as against a single point discharge, one would expect the Whites Point area to show the greatest rate of disappearance because of the higher initial dilution. The two remaining possibilities are that different rates of disappearance relate either to differences in the oceanographic conditions in the areas, or else to differences in the nature of the material being discharged. Although the Whites Point area is quite different oceanographically from the other two, there are no known conditions that suggest that Orange County and Hyperion should differ appreci- ably. On the other hand, field and laboratory data show that the effluents from the three outfalls differ markedly. SI TAS 2 Eh ROU yeh Ve ary (ey i 4G. i i Mh Oa fai eras $ : of ead ray Le ‘BOA WHE 8 Id SO eanUp & erew..7 RE OF ay es be y Lerépir Pe kty ral es A al ry ih v Me Ss Ae : £ ~ 4 ia a re a 1 ery he, om) 7 1 Ph ne a bs pen: si 70 Qualitative field observations suggest that there is a great difference in the character of the solids being discharged and in particular that these solids have markedly different settling properties. Particulate material from the effluent is visible in the boil of the Orange County outfall as small black discreet particles usually less than 1/l inch in diameter. The particles rapidly diminish in number wntil at a distance of about 1,000 feet, few are noticeable in the surface waters. Strings or patches of grease are rarely seen in this area and when such surface clots do occur, they are small and minor in extent. From the Hyperion outfall there are on most occasion large flat flocculent particles, often an inch or more in diameter in the boil and the immediate waters. The particulate material is frequently in such great quantities as to reduce the transparency to less than 2 feet with the Secchi dise and less than 1% light transmission with the transparency meter. The black floccules may remain visible in the surface layers for distances exceeding two miles, becoming consistently smaller with distance from the outfall. Although surface films of grease are not common in the waters surrounding the Hyperion outfall, they occur with greater frequency than in the Orange County area and may cover several hundred square feet of water surface. Such patches have been noted as far as ten miles from the outfall. Particles in the sewage discharged from the Los Angeles County outfall at Whites Point are similar to those seen in the Orange County area, except for the frequent occurrence of floatable objects. Large floccules are not particularly obvious, nor are they visible at great distances from the boil. However, the PP 3 aii eet eatin tee its ty aiNeo Re nbtnerg ; i Mi (pbs b od dime ie hie t i 7 f i i es “het town. i vi Pe wh w yy Mew gee cn in oe yal surface of the sea around this outfall is usually covered with large continuous patches of brown grease and stringy material. These patches may be several thousand feet in length and many hundred feet wide. Grease areas covering several hundred square feet have been seen as far as six miles from the outfall site. It appears, therefore, that each type of effluent will have its own settling characteristics and that this parameter will largely control the rate of coliform disappearance, over the periods of time significant in a disposal situation. Consequently, it is no more valid to predict what will happen in the proposed outfall on the basis of the Orange County effluent than it is on the basis of the secondary treatment effluent now being discharged in the bay. What is now needed is a study of what happens when Hyperion primary is introduced and this study should employ not only the methods already in use by our group and the Hyperion group, but should also employ radioactive tracing of the sewage field, if possible. CONCLUSIONS 1. The greatest effect of aon on the disappearance of coliforms occurs during the initial mixing of the effluent with sea water, and subsequent effects are minor. 2e Factors other than dilution are effective in reducing coliform numbers. Evidence has been obtained to show that sedi- mentation has a major role in this connection and may actually by the only other factor of significance operating over short time periods. als uk i itiw de aabord, af 2 72 3. The rate of disappearance of coliforms differs at the three outfalls studied, being fastest at Orange County and slowest at Whites Point. The differences in these rates seem to be associ- ated with the settling characteristics of the particulate fractions of these effluents. lh. It appears unwise to base any predictions of the behavior of the proposed outfall on the disappearance rates measured for the three effluents and it is proposed that similar measurements be made during discharge of primary effluent from Hyperion. Pines! se i {en Vr tue Dee La i “Ay i ans i ul