2023 California Code › Health and Safety Code - HSC › DIVISION 20 - MISCELLANEOUS HEALTH AND SAFETY PROVISIONS › CHAPTER 6.5 - Hazardous Waste Control › ARTICLE 9.5 - Surface Impoundments › Section 25208.8.

25208.8. A person who receives a notice from a regional board pursuant to Section 25208.7 or who files an application for an exemption pursuant to Section 25208.5 or 25208.13, shall submit a hydrogeological assessment report to the regional board. A qualified person shall be responsible for the preparation of the report and shall certify its completeness and accuracy. The report shall contain, for each surface impoundment, any information required by the state board or the regional board, and all of the following information:
(a) A description of the surface impoundment, including its physical characteristics, its age, the presence or absence of a liner, a description of the liner, the liner’s compatibility with the hazardous wastes discharged to the impoundment, and the design specifications of the impoundment.
(b) A description of the volume and concentration of hazardous waste constituents placed in the surface impoundment, based on a representative chemical analysis of the specific hazardous waste type and accounting for variance in hazardous waste constituents over time.
(c) A map showing the distances, within the facility, to the nearest surface water bodies and springs, and the distances, within one mile from the facility’s perimeter, to the nearest surface water bodies and springs.
(d) Tabular data for each surface water body and spring shown on the map specified in subdivision (c) that indicate its flow and a representative water analysis. The report shall include an evaluation and characterization of seasonal changes and, if substantive changes result from season to season, the tabular data shall reflect these seasonal changes.
(e) A map showing the location of all wells within the facility and the locations of all wells within one mile of the facility’s perimeter. The report shall include, for each well, a description of the present use of the well, a representative water analysis from the well, and, when possible, the water well driller’s report or well log.
(f) An analysis of the vertical and lateral extent of the perched water and water-bearing strata that could be affected by leachate from the surface impoundment, and the confining beds under and adjacent to the surface impoundment. This analysis shall include all of the following:
(1) Maps showing contours of equal elevation of the water surface for perched water, unconfined water, and confined groundwater required to be analyzed by this subdivision.
(2) An estimate of the groundwater flow, direction of the perched water, and all water-bearing strata on both the maps and the subsurface geologic cross sections.
(3) An estimate of the transmissivity, permeability, and storage coefficient for each perched zone of water and water-bearing strata identified on the maps specified in paragraph (1).
(4) A determination of the rate of groundwater flow.
(5) A determination of the water quality of each zone of the water-bearing strata and perched water that is identified on the maps specified in paragraph (1) and is under, or adjacent to, the facility. This determination shall be conducted by taking samples either from upgradient of the surface impoundment or from another location that has not been affected by leakage from the surface impoundment.
(g) An indication as to whether the groundwater is contiguous with regional bodies of groundwater and the depth measured to the groundwater, including the depth measured to perched water and water-bearing strata identified on the maps specified in paragraph (1) of subdivision (f).
(h) The following climatological information:
(1) A map showing the contours for the mean annual long-term precipitation for the surrounding region within 10 miles of the surface impoundment.
(2) Calculations estimating the maximum 24-hour precipitation and maximum and minimum annual precipitation at the facility based upon direct measurement at the facility or upon measured values of precipitation from a nearby climatologically similar station.
(3) The projected volume and pattern of runoff for any streams that, in a 100-year interval, could affect the facility, including peak stream discharges associated with storm conditions.
(i) A description of the composition of the vadose zone beneath the surface impoundment. This description shall include a chemical and hydrogeological characterization of both the consolidated and unconsolidated rock material underlying the surface impoundment, and an analysis for pollutants, including those constituents discharged into the surface impoundment. This description shall also include soil moisture readings from a representative number of points around the surface impoundment’s perimeter and at the maximum depth of the surface impoundment. If the regional board determines that the use of suction type soil sampling devices is infeasible due to climate, soil hydraulics, or soil texture, the regional board may authorize the use of alternative devices. The report shall arrange all monitoring data in a tabular form so that the data, the constituents, and the concentrations are readily discernible.
(j) A measurement of the chemical characteristics of the soil made by collecting a soil sample upgradient from the impoundment or from an area that has not been affected by seepage from the surface impoundment and is in a hydrogeologic environment similar to the surface impoundment. The measurement shall be analyzed for the same pollutants analyzed pursuant to subdivision (i).
(k) A description of the existing monitoring being conducted to detect leachate, including vadose zone monitoring, the number and positioning of the monitoring wells, the monitoring wells’ distances from the surface impoundment, the monitoring wells’ design data, the monitoring wells’ installation, the monitoring development procedures, the sampling methodology, the sampling frequency, the chemical constituents analyzed, and the analytical methodology. The design data of the monitoring wells shall include the monitoring wells’ depth, the monitoring wells’ diameters, the monitoring wells’ casing materials, the perforated intervals within the well, the size of the perforations, the gradation of the filter pack, and the extent of the wells’ annular seals.
(l) Documentation demonstrating that the monitoring system and methods used at the facility can detect any seepage before the hazardous waste constituents enter the waters of the state. This documentation shall include, but is not limited to, substantiation of each of the following:
(1) The monitor wells are located close enough to the surface impoundment to identify lateral and vertical migration of any constituents discharged to the impoundment.
(2) The monitoring wells are not located within the influence of any adjacent pumping wells that might impair their effectiveness.
(3) The monitor wells are only screened in the aquifer to be monitored.
(4) The chosen casing material does not interfere with, or react to, the potential contaminants of major concern at the facility.
(5) The casing diameter allows an adequate amount of water to be removed during sampling and allows full development of the monitor well.
(6) The annular seal prevents pollutants from migrating down the monitor well.
(7) The methods of water sample collection require that the sample is collected after at least five well volumes have been removed from the well and that the samples are transported and handled in accordance with the United States Geological Survey’s “National Handbook of Recommended Methods for Water-Data Acquisition,” which provides guidelines for collection and analysis of groundwater samples for selected unstable constituents. If the wells are low-yield wells, in that the wells are incapable of yielding three well volumes during a 24-hour period, the methods of water sample collection shall ensure that a representative sample is obtained from the well.
(8) The hazardous waste constituents selected for analysis are specific to the facility, taking into account the chemical composition of hazardous wastes previously placed in the surface impoundment. The monitoring data shall be arranged in tabular form so that the date, the constituents, and the concentrations are readily discernible.
(9) The frequency of monitoring is sufficient to give timely warning of leachate so that remedial action can be taken prior to any adverse changes in the quality of the groundwater.
(10) A written statement from the qualified person preparing the report indicating whether any constituents have migrated into the vadose zone, surface water bodies, perched water, or water-bearing strata.
(11) A written statement from the qualified person preparing the report indicating whether any migration of leachate into the vadose zone, surface water bodies, perched water, or water-bearing strata is likely or not likely to occur within five years, and any evidence supporting that statement.
(Amended by Stats. 2006, Ch. 538, Sec. 382. Effective January 1, 2007.)