Re: The Lakes at Heron EQ 07-2852 Water Availability Review
Dear_______,
This letter is in response to your submittal received by the Department on May 1, 2007, regarding the water availability for the above referenced proposed subdivision. The information submitted is inadequate for the Department to determine that proposed water supply is adequate. Please address the following comments and questions listed below. This letter also includes responses to comments submitted by local citizens on June 8, 2007.
The lot layouts submitted appear to be missing water sources for lots 76 and 78. Clarify the proposed water source for these lots and amend the lot layouts as necessary.
The west well wasn’t tested for nitrate and specific conductance as required in ARM 17.36.331(1)(b). The west well should be tested for those constituents.
Based on the exceedence of antimony in a nearby well (GWIC ID 132575), the west well should also be tested for antimony to insure it doesn’t exceed the DEQ-7 human health standard.
The pumping test information submitted indicates a relatively quick connection between the wells and the adjacent Clark Fork River. The rapid stabilization of water levels during the multiple pumping tests and the identical water level response between the river and the west well during the middle well 24-hour pumping test indicates that surface water contamination of the wells may be possible. Therefore, the applicant will be required to collect at a minimum, on sample from the west well for a Microscopic Particulate Analysis (MPA) pursuant to ARM 17.36.331(1)(d). The MPA collection, transport and analysis should be conducted in accordance with Section 6 of Department Circular PWS-5 (2002 edition). If the initial sample is classified as low risk then no additional MPAs will be required and the wells will be considered not under the direct influence of surface water. If the initial MPA sample is medium or high risk, then at least one additional MPA will be required – the final determination of the water source will then need to be based on the results of the MPAs and any other pertinent information. The MPA should be conducted at a higher flow rate than the well will be utilized as to account for long term pumping and effects of multiple wells. A flow rate of 40 to 50 gpm should be sufficient (note: this flow rate is not the rate that should be run through the filter – that should be set at 1 gpm as outlined in PWS-5).
With regards to the four constant-rate pumping tests conducted please submit the following information for each test
The method of flow rate measurement. The recorded flow rate measurements with elapsed time during the pumping test;
How far and where was the pumped water discharged to;
The static water levels prior to initiation of each test;
Submit the raw data (drawdown and recovery) for each test in electronic format; and
Clarify the units used on each of the graphs submitted – some are not clear as to the units.
The West well 6-hour test graphed data shows three different sets of data on the three different graphs (linear, semi-log, and log-log) – one shows 0.6 feet of drawdown, one shows 0.8 feet of drawdown and one shows 3 feet of drawdown. Please clarify these discrepancies. Also clarify the units on each plot submitted.
The Middle well 6-hour test graphed data shows three different sets of data on the three different graphs (linear, semi-log, and log-log) – one shows 3.75 feet of drawdown, one shows 2 feet of drawdown and one shows 0.3 feet of drawdown. Please clarify these discrepancies.
The East well 6-hour test graphed data shows three different sets of data on the three different graphs (linear, semi-log, and log-log) – one shows 4.25 feet of drawdown, one shows 2.4 feet of drawdown and one shows less than 2 feet of drawdown. Please clarify these discrepancies.
The aquifer parameters calculated and submitted with the subdivision application may not be accurate depending on the information submitted in response to comments 5 through 8 and the proper interpretation of that data.
The conclusions in the water availability report are unclear. The report states that the interference effects of multiple wells cannot be evaluated with the data collected, and that well interference may not be of concern. If the applicant cannot state that there is adequate water and provide valid justification, then the Department can not approve the adequacy of the proposed water supply.
Some local citizens have submitted comments on their own. I have summarized those comments that are related to water and provided Department responses.
COMMENT: The Clark Fork River is on the states 303(d) list – effects form additional nutrients from wastewater systems are not addressed in the application. In general the impacts to the Clark Fork River need to be addressed RESPONSE: The Clark Fork river adjacent to the proposed subdivision is listed on the states 2006 303(d) list of impaired water bodies. However, the impairments in this section of the river are not related to nutrient impacts. The sources are all related to the dam that forms the Cabinet Gorge Reservoir, the probable causes are alteration in stream side or littoral vegetative covers, dissolved gas super-saturation, other flow regime alterations and water temperature. Therefore excessive nutrients do not appear to be an issue in this section of the river. Additional information on the 303(d) list can be found at: http://deq.mt.gov/CWAIC/default.aspx . Impacts to the river will be evaluated in the Departments nondegradation review
COMMENT: The application didn’t address the following ground water information: aquifer parameters, hydraulic gradient, static water levels and conduct pumping tests. RESPONSE: Additional information regarding aquifer parameters, hydraulic gradient and , static water levels have been requested from the applicant since some of this information is missing from the original application or is unclear. Four different pumping tests (conducted on two on-site and one off-site well) were submitted in the original application (three were conducted for 6 hours and one was conducted for 24 hours) – the Department is requesting additional information to fully evaluate the results of those tests.
COMMENT: The application does not address availability of water for all 80 lots. RESPONSE: The Department is requiring additional information from the applicant to address the adequacy of the water source – see items #5 through #10 of this letter.
COMMENT: Does the developer have water rights that allow them to conduct pumping tests on the wells. RESPONSE: Water rights are administered by the Montana Department of Natural Resources (DNRC) – that agency should be contacted regarding this issue.
COMMENT: The subdivision should have a community water system. RESPONSE: If the source of water proposed by the applicant (individual wells in this case) meets DEQ requirements the Department must approve the request, and cannot require a different type of water supply.
If you have any questions, please contact me at 444-0916 or eregensburger@mt.gov.
Sincerely,
Eric F. Regensburger Subdivision Review Section
Heron-CRD
Heron Citizens for Responsible Development Heron, Montana