Code of Massachusetts Regulations › 310 CMR - DEPARTMENT OF ENVIRONMENTAL PROTECTION › Title 310 CMR 30.000 - Hazardous waste › GENERAL PROVISIONS › Section 30.675 - Probable High Groundwater Levels

Current through Register 1525, July 5, 2024
(1)
For areas in Massachusetts other than Cape Cod
:
(a)
Sand and gravel
				areas
. For estimating the probable high groundwater levels in sand
				and gravel areas in Massachusetts except Cape Cod, the following formula shall
				be used wherever practicable. Use of this formula allows for the estimation of
				the potential groundwater level rise at the facility site by correlation with
				the potential rise in an off-site observation well if the climatic trends and
				hydrogeologic conditions at the site and the well are similar. For an in-depth
				discussion of the derivation of this formula and its use see:
Probable
				High Groundwater Levels in Massachusetts
, U.S. Geological Survey,
				water Resources Investigations, Open-File Report 80-1205 by Michael H.
				Frimpter.
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where:
Sh = estimated depth to probable high
				  water level at the site;
Sc = measured depth to water at the
				  site (ground level to water table);
OWc = measured depth to water in the
				  observation well which is used to correlate with the water levels at the site
				  (ground level to water table); OWmax = depth to recorded
				  maximum water level at the observation well which is used to correlate with the
				  water levels at the site; Sr = range of water level
				  where the site is located; and
OWr = recorded maximum value of annual
				  range of water level at the observation well which is used to correlate with
				  the water levels at the site.
In the above equation, sc and
				  OWc shall be measured in the same month. The observation
				  well which is chosen to correlate with the water levels at the facility site
				  shall be among those included in the report
Groundwater Levels in
				  Massachusetts, 1936-74
: U.S. Geological Survey Open-File report,
				  massachusetts Hydrologic-Data Report 17 by Anthony Maevsky. The observation
				  well shall be located in the same type of climate and hydrogeologic environment
				  as the facility site.
Values of OWmax and
				  OWr shall be obtained from the chosen observation-well
				  record. OWmax shall be found by reviewing the historical
				  record of measurements and finding the depth from ground level to water table
				  level that corresponds to the maximum water level ever recorded at the
				  observation well site. OWr shall be determined by
				  finding the maximum water level fluctuation that ever occurred during one year
				  of recordings at the observation well (
i.e.
, the "range" or
				  the maximum difference in water table levels ever recorded during a one year
				  period).
The value of Sr shall be as
				  follows:
Sand and gravel deposits on terraces and hillsides 10
				  feet
Sand and gravel deposits in valleys 4 feet
These values represent a range of water level at the site
				  that is unlikely to be exceeded.
(b)
Areas of till
.
				For estimating the probable high groundwater level in areas of till, a series
				of measurements shall be taken to determine the high groundwater level for a
				particular year, and the following method shall be used, wherever practicable.
To estimate the maximum water level, a proportion is used.
				  That proportion is: The potential water-level rise at the site is to the
				  maximum annual water-level range at the site as the potential water-level rise
				  at an observation well is to the maximum annual water-level range at the
				  observation well, where the potential rise is the difference between the
				  highest and current water levels. For the use of the formula below, a value of
				  five feet was chosen to represent the maximum annual water-level range at the
				  site. Analysis of records of over 5000 water level measurements in 15 wells in
				  till between 1936 and 1982 show that the mean range of maximum annual water
				  levels is about five feet. For an illustration of the variables which are used
				  in the formula,
see
Figure 30.675(1)(b).
Difference between current
and maximum
								levels at site
= Range of maximum annual level at site
Difference between current and
maximum
								levels at observation well
Range of maximum annual level at
								observation well
Sc -
								Sm =
5
OWc - OWm
								OWr
Sm =
								Sc - 5 x
OWc - OWm
								OWr
Steps in the method are as follows: Measure and record the
				  water level on a weekly basis from March 15 to May 15. From the observation
				  well location map select the most representative observation well on a basis of
				  geographic proximity. From reports of the U.S. Geological Survey determine the
				  water level (OWc) in that observation well for the
				  concurrent date, the date closest to the date at which the highest water level
				  was measured at the site. Determine from Table 30.675(1)(b), provided here, the
				  maximum recorded water level (OWm) and the range of
				  annual maximum water level (OWr) for the same
				  observation well. Substitute these values of OWc,
				  OWm and OWr, and the current
				  maximum annual water level measured at the site (Sc) in
				  the formula and solve for the estimated maximum water level at the site
				  (Sm).
Based on the small available sample of 10 representative
				  observation wells in till there is a 10% chance that the maximum annual range
				  at a site would exceed the estimate by about one foot. See the range of
				  OWr in Table 30.675(1)(b).
TABLE 30.675(1)(b)
Maximum Water Levels and Maimum Annual
Water-Level Ranges for Observation Wells in Till
LOCATION
NUMBER
OWm
OWr
Andover
AJW-26
3.47
5.48
Cheshire
CJW-2
0.14
4.00
East Bridgewater
EBW-30
2.40
5.78
Great Barrington
GMW-2
5.09
5.65
Lowell
L2W-14
7.79
6.11
Middleborough
MTW-82
1.57
4.68
Northborough
NUW-38
0.96
3.58
Topsfield
TQW-1
5.64
4.49
Weymouth
XGW-2
5.25
4.44
Winchester
XOW-14
4.03
4.69
Most, but not all, facility sites will be located in one of
				  the hydrogeologic settings discussed above. As an example, a surface
				  impoundment might be located on a terrace composed largely of silt. In such a
				  case, the formula is not valid. The estimation of the probable high groundwater
				  levels shall be based upon measurements of the water level at the facility site
				  in the months of March, april and May and a best possible prediction of the
				  highest water table levels that can reasonably be expected throughout the
				  facility's operating life (and beyond if a land disposal facility). Soil
				  mottling may help to verify this prediction. In rare instances, long term
				  historical data (15 years or more) of water levels may actually be available at
				  the facility site. In these cases, the probable high groundwater levels can be
				  determined directly from this data.
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