Date: February 11, Ledyard Planning & Zoning Commission Mr. Michael Cherry, Chairman 741 Colonel Ledyard Highway Ledyard, Conn.

Transcription

1 Date: February 11, 2016 To: Ledyard Planning & Zoning Commission Mr. Michael Cherry, Chairman 741 Colonel Ledyard Highway Ledyard, Conn Subject Property: Plan Showing Quakertown Meadows Open Space Subdivision; Property of Green Falls Associates, LLC; 423 Colonel Ledyard Highway, Ledyard Conn. Plan Designed by: Dieter & Gardner Land Surveyors - Planners Plan Date: July 22, 2015 Last Revision Date: January 29, 2016, Received February 1, 2016 Date Paid: October 16, 2015 A 20 sheet set of revised plans and associated information was submitted to our office on February 1, 2016 for a proposed 37 lot subdivision/commission review. Lots range in size from 0.3 acres to 1.05 acres and are to be served by individual on-site subsurface sewage disposal systems and private wells. A previous letter of review of an earlier plan set requesting 39 lots was issued dated December 18, A copy of a report entitled Water Study, Proposed Quakertown Meadows Subdivision prepared by Andrew Adinolfi, P.E. was received and reviewed. A second document that was submitted in review of Mr. Adinolfi s report by Robert Russo, C.S.S. of CLA Engineers, Inc., was reviewed. A copy of a letter issued by John R. Martucci, P.E., addressing soil conditions and the need for providing foundation drains was received on February 3, 2016, and reviewed. A log of ground water monitoring results for Mon. Wells no. 49 through 55 during the time period of 2/7/11 through 5/3/11 was received from Peter Gardner on January 27, 2016, and reviewed along with addition monitoring data from this writer s field observations during the same period. The Ledge Light Health District (LLHD) does not issue approvals for Subdivision or Commission reviews, but our recommendations and/or comments regarding suitability of the previously stated plan/lots to accommodate the LLHD Subdivision Submission Requirements and Connecticut Public Health Code Sections B103e and B51 are as follows: 1. A detailed review of each lot with noted deficiencies, comments and recommendations was provided in my prior letter. The plans have been revised or clarified to address most, or nearly all, of my prior comments. The majority of comments addressed concerns that were not deficiencies or violations of Public Health Code regulations but were relative to potential conditions that might lead to violations of regulations or conditions that could result in nuisances to the

2 Town of Ledyard or the homeowners. In clarification of those comments the plans have been revised to note: a. All dwellings are to have 3 bedrooms and would be served by individual septic systems and wells. The systems range in size of 495 sq. ft. to 675 sq. ft. based on percolation rates of 0-10 min/in and min/inch. b. All utilities will be installed by overhead service or without the use of conduit piping that may result in an encroachment of required well or septic system separating distances. Verification of such installations may be required at the time of construction/installation. c. All perforated foundation drains are to be installed a min. of 25 ft. from all septic system components other than watertight building sewer piping. All foundation drain discharge piping will be installed using watertight pipe as specified in Table 2-C of the PHC Technical Standards and shall be placed min. of 5 ft., or greater, from any system component. It was noted that no provision for gutter discharge water was indicated. For dwellings with foundation drains, the gutter discharges may be included with those discharge pipes. For dwellings with no foundation drains, no provision for gutter discharges was made. Discharge water shall not drain toward a sewage system or well. d. Potential locations for septic tanks were noted on the revised plan sheets. On two lots, no. 18 and 26, the tanks appeared to be very close, or slightly within, the required 75 ft. setback radius from the respective wells for the properties. There was sufficient area available on both lots to move the tanks to a conforming distance. e. A number of lots had been identified as having insufficient separating distance between foundation drains or road drains and wells. The storm drainage system in Quakertown Meadows roadway has been relocated to the upgradient side of the road to provide greater setback. Although several well symbols on the plan sheets appear to be very close to, or slightly within, the min. 75 ft. well setback radius, this may be a result of the size of the well symbol used on the plan. There is sufficient area available on these lots to move the well, if necessary, to meet the required distance (Lots no. 3, 30, 31, 34 and 37). f. A number of wells are noted to be within 5-10 ft. from either driveways or driveway easements. Having a well within, or so close to, a driveway with utilities also raises the potential for physical damage to the well from vehicle driving/parking, snow plowing, utility installation, etc. and contamination due to driveway salting. It is generally recommended that wells be located further from driveways where possible. g. A number of the typical sewage systems noted are specified as Mantis leaching systems. Mantis systems are not authorized to accommodate H-20 weight loading and, as such, are not recommended to be located/installed within 5-10

3 ft. of a driveway or driving/parking surface. In most, if not all, situations on proposed lots, the driveways or systems might be moved to accommodate the protective distance, or an alternate type of system that can accommodate an H-20 load rating may be noted or installed. PROPOSED LOT DEFICIENCY, COMMENT OR RECOMMENDATION Lot #1 Quakertown -Recommend H-20 rated leaching system by driveway Meadow (QM) Lot #3 QM -Recommend H-20 load rated tank and leaching by drive. Lot #5 QM -MLSS calculation on sheet 14 of 20 not revised from prior letter (incorrect). Length of leaching shown on plan sheet 8 of 20 is satisfactory. -Recommend connect foundation drain to catch basin. Lot #7 QM -Recommend providing H-20 load rated tank and leaching or move driveway Lot #10 QM - OK Lot #11 QM - OK Lot #12 QM - OK Lot #13 QM -Recommend connecting foundation drain to catch basin Lot #14 QM -Recommend moving well away from driveway Lot #15 QM - OK Lot #16 QM - OK Lot #17 QM - OK Lot #18 QM -Septic tank shown very close to, or slightly within, the 75 ft. well radius. Sufficient area available to move tank outside radius. Lot otherwise OK. Lot #19 QM -Recommend moving well away from driveway Lot #20 QM -Restrictive depth at TH#168 was 60 in primary area, thereby, requiring MLSS calculation. With restrictive depth at 60, slope at 1-2%, HF = 28, PF = 1.2, FF = 15, MLSS = 50.4 ft. Length provided is 28 ft. Increase MLSS accordingly and provide reserve area. Alternate option might be to flip locations for initial and reserve with initial extended toward TH#176. -Recommend moving well away from driveway. Lot #21 QM - OK Lot #22 QM - OK -Recommend moving well away from driveway.

4 Lot #23 QM - OK Lot #24 QM -Leaching system relocated in accordance with prior letter recommendation. MLSS calculation on sheet 14 of 20 is unchanged from prior revision but is unnecessary due to lack of restrictive condition. System length shown on plan sheet is satisfactory. Lot #25 QM -Recommend moving well away from driveway Lot #26 QM -Septic tank very close, or slightly within, the 75 ft. well radius. Sufficient area available to move tank outside radius. -Recommend moving well away from common drive/drive easement. -Otherwise OK. Lot #27 QM -Recommend moving well away from driveway. Lot #28 QM -Primary leaching area appears to be within 15 ft. from southerly property line. Sufficient area to provide 15 ft. property line setback. -Recommend moving well away from edge of common drive/drive easement. Lot #29 QM - OK Lot #30 QM -Well shown very close to, or slightly within, the 25 ft. setback from foundation drain. Sufficient area available to move the well and still be far enough from drain, driveway and common drive/easement. -Primary leaching system within 15 ft. of northerly property line. Sufficient area is available to move system and provide 15 ft. side line setback. Lot #31 QM - OK Lot #32 QM - OK Lot #33 QM -MLSS calculation on sheet 14 of 20 incorrect but length of leaching spread on plan sheet is satisfactory. -Recommend moving well away from driveway. Lot #34 QM -Generally OK. At time of site plan development, system areas may be moved upslope to avoid dense silt around TH#206. Lot #35 QM -MLSS incorrect. Increase perc factor to 1.2 and increase MLSS to min. 50.4, accordingly. There is sufficient area on lot to accommodate the increased length. Lot #37 QM - OK Lot #437 Col Led Hwy - OK Lot #439 CLH -Additional test hole(s) will be required at time of development of site design.

5 Lot #441 CLH -OK -MLSS incorrect. Increase perc factor to 1.2 resulting in MLSS of 50.4 ft. Sufficient area available to increase system length accordingly. Lot #443 CLH Lot #445 CLH Lot #447 CLH -Due to min/inch perc rate, the required length of GST model 6224 would be 37.3 ft. rather than 36 ft., as noted. Sufficient area is available to accommodate the required length. -Sewage system concerns are satisfactory. -As noted above, a letter was provided by J. Martucci, P.E., attesting that foundation drains would not be needed on several lots, including Lot #445. The well was located less than 25 ft. from the foundation as a result that no drains were provided. Test hole #64, which was located approx. 20 ft. off the SE corner of the typical dwelling shown on sheet 11 of 20, exhibited ground water weeping into the hole at 53 and soil mottling at 33. Test hole #61, located approx. 40 ft. uphill from the proposed house, exhibited ground water weeping into the hole at 61. In all likelihood, a foundation drain may be required by the Building Official. The well would be required to be located min. 25 ft. from the drain. Sufficient area is available to provide the necessary setback. -Sewage system concerns are satisfactory. -As noted above, J. Martucci, P.E., attested that foundation drains would not be needed on this lot, therefore, no drains are shown around the proposed dwelling. Test holes #62 and #61, located approx. 25 and 45 ft. downgrade from the proposed dwelling, noted ground water mottling and actual ground water weeping at 47 and 61, respectively. In all likelihood, a foundation drain may be required by the Building Official. The well will be required to be located a min. of 25 ft. from the drain. Sufficient area is available to provide the necessary setback. h. Based upon the individual lot reviews noted above, the 37 proposed lots either meet, or could meet, the requirements of the Conn. Public Health Code relative to on-site subsurface sewage disposal systems and wells.

6 2. Ground water monitoring results from February 7, 2011 through May 3, 2011, for monitoring wells #49-55 should be included on the plan sheets to accompany perc test and test hole results. 3. Most well water in the Ledyard area is noted to have a concentration of iron, manganese or other constituents that result in nuisance conditions warranting a water treatment system to be installed. Water treatment systems require a backwash cycle with a resulting discharge of treatment wastes to a sanitary sewer or to a separate, approved leaching system. These wastes are prohibited from being discharged to a sewage disposal system or to the ground surface. They are regulated under a General Permit from the Conn. Dep t. of Energy and Environmental Protection with required coordination with the Local Health and Building Departments for sizing, siting and permitting. In addition to prohibiting their inclusion into a septic system, the Public Health Code and DEEP provide required separation distances from wells, wetlands, drains, and septic systems. Under normal circumstances, lot sizes would enable sufficient area for backwash systems to be installed meeting the required setbacks. This subdivision made no provision for such treatment backwash disposal systems and, on a number of the proposed lots, could not legally be installed, as designed, depending on the treatment system due to required separating distances. 4. As noted above, the plans depict potential well and septic locations meeting the minimum required setback distance of 75 ft. The layout results in multiple wells with overlapping protective radii in a very minimal area with sewage disposal systems scattered between these wells at the minimum separating distance. Two major concerns with this potential design involve both the quality and quantity of water available to these wells. Although the Conn. Public Health Code Section B103e(a)(4) includes a provision that No permit or approval shall be issued for any new subsurface sewage disposal system where the surrounding naturally occurring soil cannot adequately absorb or disperse the expected volume of sewage effluent without overflow, breakout or detrimental effect on the ground or surface water the Conn. Department of Public Health has chosen to reverse an earlier position that limited lot development to a capacity that would be related to the nitrogen dilution potential of the developed area. The change in regulatory control was made in recognition that the potential variables that could effect ground water quality are complicated and not necessarily capable of being reduced to the number of bedrooms or anticipated wastewater generation by a development. Albeit a very correct observation, the fact remains that we are presented with a considerable number of houses with sewage systems in very

7 close proximity to a considerable number of wells that may, over future years, become contaminated or unsuitable due to nitrogen or other constituents as a result of that density of development. The potential risk may be further expanded if water treatment systems utilizing ion exchange (salt) treatment systems are used to improve aesthetic conditions of staining, taste, etc. with the resulting discharge of concentrated brine solutions to these lots. Over time, the amount of salt added to the soils and ground water will reach into the thousands of pounds per house with a high potential for contamination of the ground water with chlorides. The consolidated demand on the available water in these clustered areas may also result in a more exaggerated or expanded zone of influence around the well drawdown areas such that the sewage systems located on the fringe of the protective radii may more aggressively impact water quality. The plan was designed with 75 ft. protective radii which is the minimum distance for a well with a withdrawal rate of under 10 gpm. Although the Public Health Code does not specify that cumulative withdrawal impacts for wells in close proximity to each other might be considered with a resultant increase in protective radius, the potential for pulling in contaminants discharged to the ground (and ground water) at the fringe of the normal setback distance should be considered possible. Wells with a withdrawal rate of between 10 gpm and 50 gpm require a protective radius of 150 ft. The Town of Ledyard has recent experience with the extension of the public water supply to the Aljen Heights area of town to replace or eliminate well water supplies that had been compromised due to nitrogen concentrations, bacteria or other conditions. Although these water quality issues may not present themselves in a near time frame, the similarities between the two developments bears consideration. 5. Another potential consideration that often goes overlooked is the consideration of water availability. Under normal development density, a well might be installed on an acre lot with no other well located within one to several hundred feet of each other. Yields of respective wells, although a function of the water bearing fractures in the bedrock geology of the area, usually have little bearing on adjacent property wells. The fracture systems within the bedrock may have little overlap or impact on other wells considering the amount of water removed. In the subject subdivision the wells are concentrated in dense clusters with respective protective radii overlapping to minimize the areas lost for sewage system installation. But, by clustering the wells within small areas, the likelihood of these multiple wells drawing from the same, possibly limited, water bearing fracture systems could result in limited yields and, possibly, a lack of available water to the houses. There is no good predictive measure to anticipate the availability of water short of installing wells and measuring their collective impact. Looking at the topography, amount of wetlands in the vicinity, looking at the relative watershed area,

8 etc. cannot provide definitive information as to the future yields of wells, much less the impact of collective withdrawal from many clustered wells. 6. As noted above, a Water Study for the Proposed Quakertown Meadows Subdivision was prepared and submitted for review. The general approach to the study was to evaluate overall precipitation recharge to the Upper Haley Basin watershed, to evaluate the average potential water use, i.e. withdrawal, as a result of 39 homes on the subject property and to, thereby, provide a water balance calculation to show that there would be sufficient water in the watershed to meet the demand of the homes. A potential drawdown calculation was provided to estimate the potential drawdown within the bedrock aquifer as a result of such withdrawal. The summary of findings suggest(ed with) a reasonable level of confidence that the Upper Haleys basin will provide an adequate water source. Of particular note are several statements in the report, including the summary statement when the engineer qualif(ies) the findings primarily based on factors relating to uncertainties inherent in estimation of groundwater flow through fractured bedrock. On page 3,para 3 while characterizing the bedrock in the area the statement is made that Bedrock fracture distribution is generally uneven, making it difficult to predict potential yield. On page 6, para 3 it is noted that flow of groundwater in fractured bedrock is difficult to predict. Actual drawdown could be greater or less depending on connectivity of the fracture network. However, drawdown predictions were made using reasonable approximations of inputs over a reasonable range the chance for interferences at the proposed subdivision would be marginally higher.. The report closes with a statement of limitations that Bedrock flow is difficult to predict. As with any bedrock well, performance of individual wells may be affected by connectivity of fractures and interferences from other wells. The report notes on page 3, para 4 that a number of well completion reports from LLHD from properties in the vicinity were reviewed with 8 of the 43 wells reported having yields above 10 gpm, with a maximum yield of 50 gpm. This writer also reviewed well completion reports from LLHD files including the information provided by Mr. Adinolfi and 21 additional well reports for properties in the vicinity covered by his report. A copy of a Ledyard GIS map of the properties was prepared using color-coded designations to note properties with well yields in the categories of: 0 3 gpm, gpm, gpm and 10.1 or greater gpm. Of particular interest was that there were 19 properties with available yield results within 1,000 ft. of the subdivision parcel, including the original farmhouse previously associated with the property. Of the 19 properties, there were 10 well completion reports noting yields in the 0-3 gpm range, 6

9 reports noting yields in the gpm range, 1 report with a yield in the gpm range and 2 properties with greater than 10 gpm yield. Of the 8 properties in the vicinity identified by Mr. Adinolfi to have yields greater than 10 gpm, 2 were within 1,000 ft. of the subject property, 1 was ¼ mile south and the remaining 3 were ¾ to 1 mile north and south of the property. There were 8 completion reports from abutting properties, including across Col. Led. Hwy to the east, of which 6 reports noted yields in the range of 0-3 gpm. 7. A report was also submitted by Robert Russo, C.S.S. with CLA Engineers, Inc., who performed a review of the Water Study. The report generally concurred with the reasonableness of the methodology used by Mr. Adinolfi and but indicated limitations of the report that were based on modeling rather than on-site aquifer testing, including well installation with yield testing and drawdown determination. SUMMARY A. The overall evaluation for this proposed subdivision is that the lot density is too great to safely accommodate properties served by on-site subsurface sewage disposal systems and wells. A number of specific concerns, as well as several general concerns relating to setback of wells and sewage system components to driveways/driveway easements, and to the lack of design consideration for water treatment disposal systems are noted above. Given the current Public Health Code regulations and technical standards, all of the lots meet, or could meet, the Public Health Code requirements for wells and sewage systems. The overriding concern, though, rests with the use of private wells and the potential for future well water quality issues and the lack of available water due to the collective demand within a very limited area. There are no Public Health Code regulations to satisfactorily protect against these conditions occurring. It is this writer s recommendation that the subdivision not be approved with individual wells, as designed. There appears to be sufficient area on the northern portion of the property within which a public water supply system with necessary wells and pumping/storage infrastructure might be constructed. This approach would remove individual wells, and their required protective radii, from the lots allowing greater flexibility for house size, location, drainage considerations and sewage system design/installation. Test wells would be installed to verify the availability of water for a limited number of wells to jointly supply the lots and safely meet the required 200 ft. protective radii for the public system. Design and planning for the public supply system would be coordinated with the Conn. Department of Public Health, Water Supplies Section. B. In the event that the Planning Commission would still consider the design with individual wells and sewage systems, the open space portion of the property to

10 the north should be designated as a potential future water supply area with rights to investigate and develop such a supply at a later time, as needed. Specific requirements to be considered for subdivision approval under this approach should include: a. Installation of the wells for the proposed lots with simultaneous yield testing and drawdown measurement over a greater time period than the currently prescribed 4 hours noted in the Public Health Code. At the time of installing wells on individual lots, test well(s) should be installed on the open space area to evaluate the potential for a future backup public water supply. For very low yield wells, Conn. Well Drilling Regulations promulgated under CGS section require an eighteen hour yield test. Results of such yield testing would be provided for consideration of the subdivision for approval to ensure that adequate water would be available for the lots based on a collective withdrawal effect. Failure to ensure that an adequate supply of water would be available would be grounds for denial of the subdivision or, at least, the reduction of lots approved. Since there are no alternate locations available for installation of replacement wells to serve dwellings experiencing a lack of water, the only viable recourse would be to develop the public supply or extend water from some other public supply. This could require an extended period of time for the planning, design and funding of such an option. It should be remembered that the Conn. State Building Code, Section P2901.1, provides that a lack of potable water serving a dwelling can be grounds for condemnation of the dwelling. b. All individual wells would be served by pumps that would limit the rate of withdrawal to less than 10 gpm. Further reductions in withdrawal may be instituted based on the resulting safe yield determined by the collective yield testing. The LLHD is currently considering a regulation or policy to require all developers or well pump installers to submit a well pump report with information detailing the pump installed, the depth of installation, the rate of withdrawal, drawdown depth, working pressures, storage tank capacity, etc. to better regulate private water systems and ensure protective radius requirements. c. Engineered site plans should be required for all properties at the time of development noting all installations/constructions including the house, accessory structures, well/water line, sewage system, water treatment backwash disposal system, utility installations (power, cable, water line), drains (footing, downspout or gutter drain discharge pipe), driveway/driveway easement (including any buried installations within easements). A surveyed as-built of the house footing or foundation should be

11 provided prior to construction of the house structure to ensure accurate placement before more extensive cost would be involved with its removal or relocation to conform to the approved site plan. A surveyed as-built site plan should be required upon completion of all construction noting all installations/constructions indicated above. *Please note that soils testing indicated on this plan are representative of actual soils conditions and additional deep test pits and percolation tests may be required by the Ledge Light Health District if the building or system location is altered and/or the suitable septic area is limited. Applicant should be aware that subdivision approval IS NOT sufficient for individual lot approval. Each lot must be reviewed by the Ledge Light Health District at the time of building permit application in order to obtain lot approval and issue a septic/well permit. Please contact me at ext. 330 if you have any questions regarding the above information. Very truly yours, George P. Calkins, R.S. Senior Sanitarian

12 Cc: P. Gardner dba Green Falls Assoc. C. Karno, R. Dalton, R. McCammon, R. Scully, R. Tetreault QUAKERTOWN MEAD SUB-LED_LTR2