Dispersion and persistence of synthetic detergents in ground water, San Bernardino and Riverside Counties : [a report to the State Water Quality Control Board, September 1964.

  • California. Department of Water Resources.
Date:
1965
Catalogue details

Licence: Public Domain Mark

Credit: Dispersion and persistence of synthetic detergents in ground water, San Bernardino and Riverside Counties : [a report to the State Water Quality Control Board, September 1964. Source: Wellcome Collection.

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    Ground Water (1962-1964) The overall area affected by ABS has not changed appreciably since the start of the study. However, considerable variation has been found in the concen- trations of ABS in ground waters of specific areas. Plates 18 and 19, ‘‘Change in ABS Concentrations, ”’ depict areas of increase or decrease in ABS concen- trations October 1962 to May 1963 and October 1962 to June 1964. The areal extent of ground waters con- taining different ranges of ABS concentrations were determined by planimetering from plates showing areal extent of ABS concentrations. Table 12 shows the ranges of ABS concentrations in mg/l and the areal extent in acres. TABLE 12 Areal Extent and Range of ABS Concentrations Area in acres—ABS in mg/l Range ABS concentrations Month (trace) Greater Total sampled 0.0 to 0.10 0.10 to 0.50 than 0.50 acreage October 1962 _____ 8,440 5,260 1,600 15,300 May i1963) Sea 8,900 3,680 1,590 14,260 August 19630===e= 7,900 5,200 1,000 13,100 June” 1964. ee 8,190 3,400 1,015 12,606 The fall and late summer sampling programs showed the areas that had concentrations of ABS in the 0.10 to 0.50 range were greater than those in the spring and early summer programs. Also, accord- ing to the findings the size of areas with ground wa- ter containing ABS greater than 0.05 mg/l and the total affected acreage have decreased since the start of the study. The table also shows a seasonal varia- tion in areas having ABS concentrations in the range of 0.00 to 0.50 mg/l. Plates 14-17, which depict the areal concentrations of ABS, again point out this cy- che shifting of ABS, with the greater than 0.5 mg/1 area showing similar configurations in May 1963 and June 1964 and in October 1962 and August 1963. From October 1962 to May 1963, the general trend was a slight decrease of ABS concentrations in the Bunker Hill Basin northeast of the San Ja- cinto fault and an increase in the Colton Basin be- tween the San Jacinto fault and the Rialto-Colton Barrier along the floodplain of the Santa Ana River. The area containing ABS greater than 0.5 mg/] in the Colton Basin increased since the start of the study from 0.05 square mile to 0.49 square mile in July 1964. This could be attributed either to heavier pumping in the area or to the effects of the added discharge by the City of San Bernardino Treatment Plant No. 2 to the Santa Ana River, starting in 1959. The final sampling in June 1964 indicates that since the start of the study, the area showing ABS ranging from 0.10 to 0.50 and greater than 0.50 mg/1 reflecting the influence of plant No. 2 discharge. The ABS front also showed slightly increased concentra- tions in Riverside Basin southwest of La Loma Hills at the Riverside and San Bernardino county lines and in the Riverside Basin southwest of La Loma Hills. The trend of a slight decrease in ABS con- centrations in Bunker Hill Basin, in the vicinity of Loma Linda and in the East Riverside Mesa, south- east of La Loma Hills, continued during the period of study. In spite of increased discharge flows, the area af- fected remained essentially the same, and the heavi- est pollution of ground waters followed the floodplain along the Santa Ana River beginning at the San Jacinto fault and extending downstream to Riverside Avenue, a distance of approximately 6 miles. With the present discharges and heavy pumping extrac- tions in the area, it is doubtful that the pollution area will expand to any considerable amount in the foreseeable future. Vertical Profile of ABS Concentrations To determine the vertical profile of ABS concentra- tions in the ground water, the four 8-inch test wells and two test holes for piezometers, described previ- ously, were drilled. Figure 12 shows the variation of ABS concentra- tions with depth in ground water from test wells No. 1 and No. 2. Graphs were not prepared for test wells No. 3 and 4 because no variation of ABS with depth was exhibited in these wells and ABS concentrations were too low (0.10 to 0.20 mg/l) to indicate any sig- nificant trends. In well No. 1 ABS concentrations in the winter and spring showed considerable variation among depths and registered the highest values of the year. In the summer, they showed the least variation among depths and recorded the lowest values. ABS concen- trations with depth in well No. 2 showed a reversed pattern, with the high concentrations occurring in the summer and lower values in the winter. These trends may be attributed in part to two factors: ABS adsorption on soil varies with concentration and ve- locity of flow and pumping well fields in the vicinity create pumping depressions and ground water divides that alter the inflow velocities and amounts of dilu- tion water available. Plate 20 shows the average ABS concentration of three samplings of the piezometers installed by the department. No significant trend of ABS variation with depth was shown, and the low concentrations indicate that little or no percolation of ABS-laden waters from the shallow to the deeper zones takes place near the San Jacinto fault.