GUIDELINES FOR HYDROGEOLOGICAL STUDIES AND STANDARDS FOR PRIVATE SERVICES

Transcription

1 GUIDELINES FOR HYDROGEOLOGICAL STUDIES AND STANDARDS FOR PRIVATE SERVICES June 2000 Page 12

2 PART 1 TABLE OF CONTENTS INTRODUCTION...1 PART 2 PRIVATE SERVICING GUIDELINES PRIVATE SEWAGE DISPOSAL SYSTEMS PRIVATE WELLS WATER SUPPLY REQUIREMENTS Quantity Quality MINIMUM LOT SIZING...5 PART 3 REGIONAL GUIDELINES FOR CONDUCTING HYDROGEOLOGICAL STUDIES INTRODUCTION TECHNICAL REPORTS Preliminary Investigation Report Hydrogeological Study Report...16 PART 4 PRIVATE WATER SUPPLIES INTRODUCTION PRELIMINARY INVESTIGATION REPORT...17 Page 13

3 4.2.1 General Water Quantity Water Quality Well Construction Adjacent Lands & Water Uses Other Considerations HYDROGEOLOGICAL STUDY REPORT ADDITIONAL INFORMATION...28 PART 5 PRIVATE SEWAGE DISPOSAL SYSTEMS 5.1 INTRODUCTION Designated Areas Under Notice 3/ Sewage System Impact Evaluation PRELIMINARY INVESTIGATION REPORT Site Suitability Ground Water Quality Assessment On-Site Predictive Assessment Residential Development Off-Site Predictive Assessment HYDROGEOLOGICAL STUDY REPORT ADDITIONAL INFORMATION...41 APPENDICES...60 PART 1 Page 14

4 INTRODUCTION This document is intended to provide information to those persons who are seeking approval to develop land by way of private water supplies and/or private sewage disposal systems (septic systems). Such approvals are typically associated with plans of subdivision, condominiums, official plan amendments, severance applications and any other forms of development plans which would be based on individual private wells for water supply and/or on individual private subsurface sewage disposal systems. Information is also provided regarding the ground water and surface water interests of other agencies. For the purposes of approving development on private services, the Ministry of the Environment and Energy (MOEE) has delegated responsibility dealing with such matters, to the Regional Municipality of Halton and administered by the Halton Regional Health Department. The information contained in this document is, for the most part, generic in nature and is not intended to provide detailed methodologies for site specific studies. These will need to be developed on a case by case basis for individual development applications by the proponents and/or their consultants. By following the detailed procedures in this document, developers, together with Halton Region staff, will be able to confirm the private servicing potential of development properties. Private servicing capability is a prerequisite to any rural area development. Therefore, other land use planning concerns including Regional and local official plans and zoning and impacts on agriculture, mineral resources, hazard lands, environmentally sensitive areas and roads should be considered after site servicing capability is confirmed. The other planning matters should be integrated with servicing after the site servicing capability has been determined. Halton Region has been delegated by the Minister of Municipal Affairs as the approval authority for local Official Plans and amendments and also land development applications including subdivisions, condominiums, land severances and part-lot control exemptions and others. The Region evaluates and approves these various plans and development applications in comparison to the Halton Region Official Plan and associated policies and guidelines. Plans and applications for development on private services are only approved where the Region's private servicing requirements have been successfully incorporated. Where Regional water and wastewater services are not available, the Regional Official Plan requires all developments to be self-sustaining on private individual water wells and private individual sewage disposal systems. Partial servicing is permitted in some exceptions. Neither Public nor private Page 15

5 communal servicing is permitted. PART 2Error! Bookmark not defined. PRIVATE SERVICING GUIDELINES EVALUATION OF PRIVATE SEWAGE DISPOSAL SYSTEMS This section refers to conventional septic tank and tile bed systems, defined in the Ontario Building Code Act as the standard for development evaluation. The Region does not support new developments based on other types of private sewage disposal systems. Once new lots are created and registered, the approval of new private sewage disposal system installations is administered by the local municipality as part of the building permit process. (i) (ii) (iii) All land areas designated as sewage system envelopes to be used for the installation private sewage disposal systems must meet the minimum dis tance requirements pursuant to the Ontario Building Code. New development approvals on private sewage disposal systems require a sewage system envelope of 700 square metres is maintained of vacant and suitable land be set aside and protected to permit the adequate installation of a conventional septic tank and tile bed system. The tile field(s) must be adequately separated from all water supplies (wells) to meet the minimum requirements of the Ontario Building Code and Ontario Regulation 903 (Wells), made under the Ontario Water Resources Act and as amended from time to time; or such greater distance as the Region may determine, based on such factors as topography, drainage, water table, or soil conditions, placement of services etc. 2.2 PRIVATE WELLS 1) Well construction and abandonment requirements shall be those established by the Ministry of the Environment and Energy in the Ontario Water Resources Act and Ontario Regulation 903 (Wells) made thereunder and as amended from time to time. 2) All Land Division Committee decisions to approve individual residential severances on a private water supply, approval is contingent upon compliance with the Regional Health Department's requirement that an "Adequate Private Well" be constructed on the proposed lot. Wells must be constructed in accordance with the requirements of Ontario Regulation 903, (Wells). Wells must also meet the requirements of the Regional Health Department with respect to both quantity and quality as described below. In such cases, the well driller's report, laboratory results of water analysis and inspections by Health Department staff will form the basis of evaluation. The Regional Health Department will advise the appropriate Municipal Building Department as to whether a particular well meets regional private well water standards and whether the owner/applicant will be required to install a water storage tank (supplemental storage system) for potable water and auxiliary pumping system. 2.3 WATER SUPPLY REQUIREMENTS Quantity The Medical Officer of Health (MOH), in carrying out his responsibilities under the Health Protection and Promotion 1 Reference Appendix H - Urban & Rural Servicing Guidelines Page 16

6 Act, must determine the adequacy of domestic water supplies. The following criteria will be used to make this assessment. (a) (b) (b) (c) Wells with a yield of 13.7 Litres/minute (three I.G./Min.) or greater is considered to be adequate for normal domestic demands. Wells with a yield of less than 4.5 Litres/minute (one I.G./Min.) are considered to be inadequate to meet normal domestic needs. Wells with a yield between 4.5 Litres/minute (one I.G./Min.) and 13.7 Litres/minute (three I.G./Min.) may be approved provided that a water storage tank and auxiliary pumping system are installed to manage peak demands. Wells with a yield greater than 4.5 Litres/Minute may be considered inadequate where there is a seasonal water supply problem and/or there is the potential for interference between existing offsite and proposed/existing on-site wells, existing or proposed private sewage disposal systems and other groundwater uses as determined by the hydrogeological assessment described in this document Quality A water supply well will be considered inadequate with respect to quality where: (a) (b) (c) a health related parameter of the Ontario Drinking Water Objectives is exceeded; or where an aesthetic parameter of the Ontario Drinking Water Objectives is exceeded and is above the concentration considered treatable by means of a private water treatment system or, a health hazard is anticipated due to well construction, or proximity to a private sewage disposal system or other source of pollution (ie: feed lots, salt storage, industrial sites, etc.) and/or where the Region determines that costs are unreasonable to produce and maintain a satisfactory water supply. 2.4 MINIMUM LOT SIZING (a) General Minimum lot sizing refered to in this section deals with lot sizes solely private servicing. Larger lots than those necessary for private servicing may be required for other, non-servicing related reasons such as official plan or zoning by-law requirements. These Guidelines apply to the creation, expansion and/or alteration of boundaries of private serviced lots. Some existing lots do not conform to this guideline and development may be restricted or denied based on the ability of the lot to be "self-sustaining". The term "self-sustaining" referred in this section, means a lot of sufficient size and shape to accommodate the dwelling, private well and private sewage disposal system envelope; while maintaining compliance with Ontario Building Code requirements and O.R. 903 made under the Ontario Water Resources Act. (b) Single Family Residential Lots All new residential lots within designated Hamlets and Rural Clusters where overall hydrogeological studies have been carried out must meet the minimum lot size recommendations of the overall study, unless more detailed sitespecific studies carried out to Halton's satisfaction recommend a smaller lot size. All residential lots within plans of subdivision located outside of Hamlets and Rural Clusters shall meet the minimum size recommendations of the site-specific hydrogeological investigations carried out to Halton's satisfaction. Page 17

7 For individual residential severances, it is not Halton's usual practice to require submission of site-specific hydrogeological studies, but in unusual conditions where servicing feasibility is suspect, such a requirement may be required. It is normal practice for the Health Department to evaluate the merits of a severance application of a particular size based on "minimum physical requirements" plus additional information concerning density and proximity of existing development in the area, lot shape, soil conditions, topography, water table, drainage, available hydrogeological information and the performance of existing private services in the area. (c) Industrial or Commercial Development For industrial or commercial plans of subdivision on private services, lot sizes will be determined based on the hydrogeological studies carried out to Halton's satisfaction. For individual severances for non-residential uses, a hydrogeological study may not be required if the proposed use is small scale with very few employees and only domestic water requirements. Applicants should contact the Halton Regional Health Department to determine the needs for a hydrogeological study prior to the commencement of the on-site investigation. Conditions of Approval As a condition of approval for all rural estate plans of subdivision, to be serviced by individual private services, the owner/applicant will be required to establish a private well, acceptable to the Regional Health Department, on each draft approved lot prior to Final Approval. In the case that no Regionally acceptable well can be established on any draft approved lot, said lot shall not be registered as a separate building lot, but will be either: a) merged with an abutting lot or b) the subdivision will be redesigned to the satisfaction of the Region. Proponents for industrial and commercial plans of subdivision may, as a condition of draft approval, enter into agreement with Halton pertaining to the operation of private wells and sewage disposal facilities and their relationship to site specific constraints or uses which may affect future operation. The agreement will be registered on title and fto ensure the terms will apply to successive owners. PART 3 Error! Bookmark not defined. REGIONAL GUIDELINES FOR CONDUCTING HYDROGEOLOGICAL STUDIES 3.1 INTRODUCTION In developing this guideline, consideration has been given to the most recent MOEE guidelines and policies. All applications for development on private services will be assessed in accordance with the requirements of this part of the guideline. Preliminary Investigation Page 18

8 Prior to draft approval or an official plan amendment, the Region requires that a Preliminary Investigation be undertaken and the results documented to demonstrate that the proposed privately-serviced project may be accommodated on the development lands and will not have adverse effects on groundwater sources. The most common components of the Preliminary Investigation Report in support of a land development application or Official Plan Amendment include: a) study of existing geological, hydrogeological and soil information, b) soil testing and description through test pitting and/or soil borings, c) ground water level measurement through ground water monitor and test well installation, d) aquifer identification through test drilling, e) aquifer testing through test well and observation well installation, pump testing, monitoring on-site and private off-site wells during pump testing, f) ground water quality sampling of on-site ground water monitors, test wells and off-site private wells. g) on-site hydraulic testing of saturated soil through ground water monitors, h) surficial soil identification through test ie: excavations/boreholes i) laboratory grain size analysis of soil samples and j) elevation survey of selected on-site and private wells The above noted information is used to: a) interpret the hydrogeological conditions beneath the property, b) calculate the quantity of ground water available to water-supply wells on the property c) determine the prevailing ground water quality on the site and possibly nearby private wells and/or ground water monitors, d) predict the loadings of nitrates from subsurface sewage effluent disposal to the groundwater system e) assess the suitability of soil conditions and identify limiting factors (bedrock, water-table proximity) on the property for sewage effluent disposal for purpose of sewage system design, f) calculate the potential impact on the shallow and/or deep ground water system with respect to quantity and quality resulting from the proposed development and g) determine the extent to which predicted ground water impacts from the development will affect existing on and off-site groundwater sources natural features such as surface water, wetlands or natural areas. Hydrogeological Study Page 19

9 As a condition of the draft approval or the Official Plan Amendment approval, the Region requires a Hydrogeological Study be carried out to establish that wells, yielding adequate supplies of potable groundwater on each lot are feasible. The study will also confirm that the proposed development will have no adverse quality and quantity impacts in the existing groundwater sources adjacent to the proposed development. In some instances, the Region may require the Hydrogeological Study prior to draft approval. The most common components of the Hydrogeological Study include: a) pump -testing and water-quality sampling of the water-supply wells installed on the individual lots of the proposed development. b) water-level monitoring of each pumped well, and nearby on-site observation well(s) and off-site private well(s) within the potential drawdown-influence catchment of the pumped well. c) elevation survey of selected on-site wells and private wells near the proposed development. d) pump testing of any private well that experiences significant drawdown during any on-site well test. e) background quality testing of existing private wells downgradient from the proposed development where adverse impacts are indicated by the mass-balance evaluation. The above noted information is used to: a) establish that each lot can provide a perennial water supply. b) determine the off-site quantity impact and to develop Region-acceptable mitigation procedures between the applicant and the affected persons. c) corroborate the initial interpretation of groundwater flux and movement beneath the site and verify that existing downgradient groundwater sources and natural features will not experience future adverse ground water quality impacts resulting from the proposed development. Processing Fees The proponent will be required to pay the following costs associated with the assessment of his/her application: a pro-rated cost of the overall Hamlet Study costs associated with carrying out the Preliminary Investigation Report and the Hydrogeological Page 20

10 Study. costs associated with the Region's review of the Preliminary Investigation Report and the Study by an independent hydrogeological consultant/retained by the Region, and associated meetings with the proponent Page 21

11 3.2 TECHNICAL REPORTS Both the water-supply evaluation and the sewage-impact assessment of either the Preliminary Investigation Report and the Hydrogeological Study Report must be submitted for review to the Regional Health Department. This process ensures that water and sewage impact assessments have been comprehensively evaluated by the proponents consultant Preliminary Investigation Report Reports in support of development utilizing private wells and private sewage disposal systems must include the following information: i) Physical Setting a) Provide regional and local maps which show site location and orientation with Lot and Concession Numbers. Use maps of the scale that best describe the site and local features from the Ontario Base Mapping or National Topographic Series. b) Describe local land uses and servicing, surface topography, surface drainage conditions, environmental features, wetlands, watercourses, and flood plains within at least 500 metres of the site. c) Identify present and previous on-site land uses, and determine possible contamination sources (spills, refuse, fertilizers) that may necessitate a formal environmental audit. ii) Water Supply a) Describe the regional hydrogeologic setting. b) Plot and locate representative well(s), observation wells and wells on an appropriate scale (normally for areal well plots 1:10,000 maps should be used) c) Tabulate local well depth (recorded and unrecorded) listing all relevant information (ie: log, depth, static level, pumping water levels, pump setting, rated pumping capacity and screen(s). d) Prepare at least two cross sections extending through the development lands and identify preferred aquifer for water supply. e) Estimate the recoverable on-site recharge and comment on the potential of aquifer mining. f) Assess the susceptibility of the proposed water-supply aquifer to surface-derived contamination. Page 31

12 g) List the well construction particulars for each on-site test well, including: i) detailed diagrams showing casing length and wall thickness, screen slot size, length and diameter, top-of-casing elevation ii) MOEE well logs h) Provide pumping-test particulars for each on-site well, including: i) graphical plots of the step test and the prolonged aquifer test (at the design for at least six hours). ii) analysis of the pumping test results (by Jacob or Theis method) with justification of selected methodology. The analysis should discuss and identify the short-duration and sustained (perennial) capabilities of the tested wells. i) Discuss the water quality obtained at each test well in regard to the groundwater potability and treatment requirements. j) Evaluate the observed water-level responses in the adjacent private wells and determine the possibility of future water-supply disruptions following completion of the proposed development. k) Advise on possible mitigation measures where existing well interference occurred during on-site testing. iii Sewage Disposal a) Plot locations of test pits/boreholes and water-table quality monitors, areas of shallow saturation, and delineate distribution of major surficial soil types (excepting topsoil and/or upper 0.5 metre soil veneer). b) Provide graphical plots of grain-size determinations of representative soil samples. c) Identify major soil types (below the upper veneer) influencing the infiltration of precipitation (groundwater recharge) beneath the development lands. d) Provide preliminary documentation on the leaching-bed design and tile-bed area requirements for sewage-disposal systems conforming to the Ontario Building Code. iv Quality Impact Assessment Page 32

13 a) Prepare potentiometric maps for the shallow groundwater system and for the water-supply aquifer, showing the lateral groundwater gradients and direction of groundwater movement beneath the site and defining the area downgradient of the property limits. b) Determine the appropriate infiltration rate through the surficial sediments, recognizing the distribution of the major soil types and possibly the vertical gradients established between the defined shallow and deep groundwater systems. c) Calculate the allowable development for the proposed residential or commercial/industrial development, following the Region-approved direct dilution procedure. d) Estimate the nitrate impact on downgradient sources, following the Region-approved dilution procedure Hydrogeological Study Report a) Summarize the pumping-test and water-quality results for each of the private water-supply wells and confirm that adequate supplies of potable water may be realized on each lot of the proposed development. b) List the on-site monitoring results and advise on the significance of the observed water-level responses. c) Where significant interference is anticipated, provide a mitigative procedure acceptable to the impacted persons and the developer. d) Review the assembled nitrate values for the individual wells and confirm the development density established in the previous Preliminary Investigation Report. e) Obtain water-level elevations of selected individual wells to confirm the potentiometric surface and groundwater flow and flux within the supply aquifer established in the previous Preliminary Investigation Report. f) Verify that adequate direct infiltration and/or underflow is available within the defined groundwater system so that downgradient groundwater sources will not experience adverse nitrate increases as deduced in the Preliminary Investigation Report. PART 4Error! Bookmark not defined. PRIVATE WATER SUPPLIES Page 33

14 4.1 INTRODUCTION Prior to final approval, development proposals which require an on-site source of potable water will require a complete hydrogeological assessment to determine: a) the availability and sustainability of adequate groundwater supplies with respect to quantity and quality; and b) the potential for interference between water supply wells, existing off-site and proposed on-site wells, existing or proposed sewage effluent disposal systems, and other uses (e.g., for maintenance of stream flows where applicable). This guideline describes the position of the Region regarding the assessment of water supplies for developments on individual private wells. The guideline is based on past experience with development utilizing individual wells, and reflects the need to ensure the future owners of lots or homes have a high probability of being able to obtain adequate quantities of potable water for domestic consumption over both the short and long term. This guideline applies to development proposals for residential development involving individual private well water supplies. Development agreements between the proponent and the municipality, shall be used to bind development to the recommendations of approved hydrogeology studies. This guideline also applies to condominiums and to industrial, commercial or institutional developments where water is used for human consumption and the taking does not exceed 50,000 Litres in any day. The Region should be contacted for information on the applicability of this guideline to other types of privately-serviced developments. 4.2 PRELIMINARY INVESTIGATION REPORT General A Preliminary Investigation Report will be required by the Region prior to recommendation of draft approval for plans of subdivision and condominium, and may be required prior to approval of official plan amendments which would permit development on private services. The study must be performed and a report submitted to the Region at the time of circulation of the proposed Official Plan Amendment or plan of subdivision. The report must address concerns relative to the following: Future residents must be provided with water for domestic consumption that is of acceptable quality and of adequate quantity. Appropriate well construction techniques must be followed in order to minimise the possibility of well water quality degradation. Developments must not result in water quantity interference conflicts between users in Page 34

15 the development and users on the adjoining lands within 200 metres from any on-site well. With respect to quality, each test well must provide water that is safe and aesthetically suitable for human consumption. The suitability of the water for domestic use is determined by comparing the results of the analysis of ground water samples from test wells with the applicable ODWOs (listed in Part 5 - Appendix A). With respect to quantity, each test well must provide sufficient water for normal domestic purposes. This will be determined mainly on the basis of data from pumping tests in test wells. (Reference: Part 2). Draft approval will depend on the completeness and accuracy of the Preliminary Investigation Report. If the Preliminary Investigation Report is found to be incomplete, or provides insupportable interpretations the Region will advise the proponent by letter with regard to the outstanding issues. The advice and recommendations must not be construed as conditions of approval but rather as suggestions for those cases where the proponent wishes to continue to pursue approval. The Region may not undertake its review until such time that a report satisfying the requirements of this guideline has been submitted. During the Preliminary Investigation Report, the site assessment to establish groundwater availability and quality must be undertaken as follows: i) The minimum number of test wells to be pumped and sampled will be: 3 for sites up to 15 hectares in area; 4 for more than 15 and up to 25 hectares; 5 for more than 25 and up to 40 hectares; for more than 40 hectares, one additional test well for each additional 20 hectares or portion thereof. Where a development comprises five lots or less, the Region should be contacted to determine if fewer test wells are acceptable in defining the site conditions. However, as many as one test well per lot may be required by the Region for any development where ground water quantity or quality is considered marginal with respect to domestic requirements. ii) The areal distribution of test wells must be such that hydrogeological conditions across the site are adequately represented. More than the minimum number referred to in section i) above may be required, depending on the areal configuration and hydrogeological complexity of the site. iii) Consideration must be given to past or present land uses. Existing improperly abandoned wells are to be identified since they may impact on ground water. Moreover, any contaminant spills on or adjacent to the site which may affect water quantity or quality should be identified and evaluated for their impact on ground water. The test wells are to be located in an area which would permit a proper assessment of these impacts. The Preliminary Investigation Report should include recommendations for proper abandoning of existing improperly abandoned wells, and test wells which are not used for subsequent water supply in the future. Page 35

16 iv) Test wells must be located and constructed in such a way as to permit the prediction of the quantity and quality of ground water which domestic wells will supply in the future. Accordingly, the construction of these wells must be typical of wells which will be used in the development in the future, and must comply with MOEE and Region requirements as well as any additional specifications recommended by the consultant. Consideration should be given to having at least one of the test wells drilled to depth to determine the stratigraphic sequence and the presence of deeper aquifer zones. This information can then be used in determining the preferred aquifer to ensure longevity of the water supply. Existing water wells located on the site or in the immediate proximity of the site may be used as test wells, provided they fulfil i) to iv) above, and are fully incorporated into the well water quantity and quality testing programs described in the sections below. The use of existing wells and of the data obtained from them must be justified in the report as being technically appropriate; however, there must be at least one acceptable test well, new or existing, located on the site. Such wells which are to be used must have a water well record which has been accurately and fully completed. The integrity of the well and its record are essential to ensure that comparison is being made on the basis of reliable information, and that wells being established on the development site will not be compromised. If the consultant and licensed well contractor properly locate and construct the test wells, or if there are pre-existing wells on the property which meet the requirements of iv) above, the developer may use them later as domestic water wells. They must, however, yield potable water and meet the construction requirements indicated in the approved study recommendations, which are implemented by provisions in the development agreement between the municipality and the proponent. If any such wells are not to be maintained for future use, they must be properly abandoned as required by Ontario Regulation 903. Abandonment must be recommended in the hydrogeological study report and must be implemented by the development agreement. To ensure that the recommendations of the report are properly implemented, the consultant's report may include recommendations for supervision of well construction by a qualified consultant at the time the well is being constructed by the licensed well contractor Water Quantity Each of the test wells constructed during the Preliminary Investigation Report must be subjected to a pumping test. The tests may be done sequentially, using the other wells as observation wells, or several wells could be pumped simultaneously. Consideration should be given to pumping a test well at the total subdivision water demand rate (if possible) in order to clearly demonstrate the capacity of the aquifer to supply the anticipated demands. Pump Test Procedure During the Preliminary Investigation, the following pumping test procedure is required at each test well site: Page 36

17 a house-to-house survey shall be undertaken to locate accessible water supply wells in the vicinity of the proposed development. Accessibility of the well for monitoring shall be the responsibility of the property owner. Should the well remain inaccessible or should the owner not provide permission for monitoring, the consultant shall document such circumstances in his report. the test wells shall be fully developed prior to the pumping test in order to establish the prevailing turbidity levels in the aquifer. the test well shall be step tested at three rates up to the maximum well or pump capacity. If the water taking during the test will exceed 50,000 L/day a temporary Permit To Take Water will be required for this type of test. Sufficient information and time should be given to MOEE staff for evaluation and issuance of the Permit if required. Consideration must be given to where the pumped water is to be discharged, in order to avoid artificial recharge of the pumped aquifer and any other adverse environmental impacts. the test rate shall be at least the minimum rate discussed in the following subsection. the pumping test must begin with a static water level and must be performed at a fixed rate (±5%) for a minimum period of six hours 2 (longer where supplementary storage systems are necessary) of "continuous" pumping (no stoppages); water levels must be monitored in the test well and any accessible wells within 200 metres at an appropriate frequency; water must be discharged at an appropriate distance from the test well to ensure that artificial recharge does not occur; immediately following the pumping test, water level recovery must be monitored in the test well until 95% recovery occurs or for 24 hours, whichever is less. Where sufficient recovery does not occur, the issue of the long-term safe yield of the aquifer is especially significant and must be addressed in the Preliminary Investigation Report. Should a drawdown exceeding 0.5 metres be recorded in an off-site well during the above testing, the consultant shall undertake the pump testing of that well to ascertain the effect of such drawdown on the water-supply availability at the impacted residence or facility. If water-supply disruptions are observed/predicted, the consultant shall document the proposed mitigative commitments between the affected person and the developer in the Preliminary Investigation Report. Calculation of Minimum Test Rate and Well Yield The minimum pumping test rate and well yield required for a particular development must be calculated as follows:. 2 The minimum duration of six continuous hours incorporates safety factors with respect to seasonal variables. Page 37

18 The per-person water demand shall be 450 Litres per day. Peak demand occurs for a period of 120 minutes each day 3. This is equivalent to a peak demand rate of 3.75 Litres/minute for each person. The basic minimum pumping test rate is this rate multiplied by the "likely number of persons per well" which, for a single family residence, shall be the number of bedrooms plus one. Unless it is otherwise established to Region satisfaction, a minimum of four bedrooms shall be used in the calculation to calculate the daily and peak demands. The only instance where a rate lower than the above rate may be used is where preliminary results indicate that the pumping test rate cannot be sustained in the long term, and consideration is given to systems which would compensate for low well yields. In this case, the test rate may be decreased to a rate not less than 4.5 Litres/minute, but the pumping duration must be proportionately increased such that the total volume of water pumped equals the volume that would have been pumped if the test had been conducted at the above calculated minimum rate for a continuous six-hour period. The yield requirement must then be applied to the well and to the compensatory system on a daily basis. These systems and any special water treatment devices that may be necessary for their proper functioning must be fully described in the report. An auxiliary system will include storage and repressurization and will be required where the test rate is less than 13.7 litres/minute. It is recommended that the storage system be sized to compensate for peak daily use and any lawn irrigation. Regardless of whether systems are required to compensate for low yields, new domestic wells will be required to sustain repeated pumping at the test rate and duration at 24-hour intervals over the long-term. Where a test well can safely provide water at the calculated rate, it is not acceptable to conduct a pumping test at a lower rate and subsequently recommend the use of a system to compensate for low well yield simply in order to limit the migration of poorer quality water into the well. Consultants must provide a statement in the Preliminary Investigation Report indicating that, in their professional opinion, the probable well yields determined on the basis of their investigations are representative of the yields which residents of the development are likely to obtain from their wells in the long term Water Quality The consultant must obtain and analyze sufficient raw-water quality samples during the pumping test on each test well to determine the physical, chemical and bacteriological quality of the water. At least one sample must be collected during the last hour of the test. The consultant may wish to periodically obtain additional samples during the pumping period, since the consultant must address water quality changes over time and demonstrate that the water quality data are representative of the long-term quality. Prior to any sampling testing for bacteriological water quality, there must be no chlorine residual in the groundwater. 3 Refer to page 5 of the MOEE publication entitled "Water Wells & Ground Water Supplies in Ontario", The per-person daily demand use here is the upper limit of the estimated range. Page 38

19 The consultant shall conduct chlorine residual tests at the well head and shall document that zero chlorine residual was obtained and the time that bacteriological samples were obtained. Where there are wells in nearby established developments, information is to be obtained from residents, where possible, and other sources regarding water quality problems. If on-site sewage systems are used in the existing development(s) and are also to be used in the proposed development, well water samples from the existing development should be obtained and analyzed. The consultant should use this information to predict the impact of the proposed on-site sewage systems on water quality within the proposed development. Water quality may vary between aquifers or with depth in the same aquifer. The consultant should recommend appropriate well construction and must comment on the potential for cross-contamination between aquifers. Shallow and/or unconfined aquifers are susceptible to contamination from sources located at or near the ground surface. If wells are to be constructed within such aquifers, and especially where individual on-site sewage systems are also proposed, the consultant must address the risk of contamination and recommend measures which will reduce that risk. The minimum set of parameters for which the analyses must be performed is listed in the Part 5, Appendix A. Analysis procedures must provide results below the applicable Ontario Drinking Water Objectives. Other parameters, such as heavy metals, pesticides, tannins, sulphide, phenols, and fluoride, may be required by the Region. The consultant must also determine whether conditions specific to the site or its surrounding area require the inclusion of additional parameters. Complete documentation of sampling times, any on-site analytical methods, and all analytical results must also be included in the report. If methane or other potentially hazardous gases are encountered during the water supply assessment, the consultant must make recommendations to adequately control this hazard in the Preliminary Investigation Report. Note: Where health-related ODWOs or treatment limits for aesthetic ODWOs have been exceeded, the areas which the relevant test wells represent may have to be excluded from the proposed development site. In this case a justification for the selection of the boundary of the site is required. Treatment Systems For some aesthetic parameters, the ODWOs may be exceeded provided that concentrations are below the treatment limits noted in Table 3, Part 5, Appendix A. The Appendix lists these parameters, the limits for treatment and some comments on treatment methods. In cases where raw water sodium levels exceed 20 mg/l, warning clauses should be registered on title. In addition, if water softening is utilized to reduce hardness, a warning should be registered on the title with a recommendation that a separate tap, which by-passes the softener, be installed to supply unsoftened drinking water. The treatment systems mentioned in Table 3, of the Appendix A, are suggested for treatment for single parameters. When treatment for more than one parameter is required, the systems suggested may not be appropriate due to Page 39

20 treatment process interferences. The consultant must supply recommendations regarding the type of treatment required Well Construction Construction specifications for future domestic wells in the proposed development must be addressed by the consultant in the hydrogeological report. Minimally, the construction of both the test wells and future domestic wells must comp ly with Ontario Regulation 903 made under the Ontario Water Resources Act, and with municipal requirements - where applicable. When on-site sewage systems are proposed, or when they already exist on adjacent property, protection of the wells from contamination by effluent must be addressed. When shallow and/or unconfined aquifers are to be used, the consultant must recommend construction specifications and well locations to address the issue of the susceptibility of such aquifers to contamination from sources at or near the ground surface. Well locations must be selected in order to minimize the impacts on the location of leaching beds on adjoining lots. The consulting hydrogeologist should try to work with the planner or site engineer in producing the development plan. Well and sewage systems would then be incorporated at an early stage in the site design, thereby optimizing site resources for water supply and sewage treatment. Storm water management should also be taken into consideration when siting a well and a sewage system. Water quality may vary between aquifers or with depth in the same aquifer. The consultant should recommend appropriate well construction, methods and requirements, and must comment on the potential for cross-contamination between aquifers. The consultant or the Region may wish to recommend additional site-specific construction criteria and/or supervision of well construction by qualified staff. In studies in which the consultant's initial findings show that water quality or quantity standards cannot be met without special well construction specifications, the initial data which led to these conclusions must be included in the report. The structure of the test wells on which the final quantity and quality data are based mu st meet these specifications and the wells must be tested according to the procedures stipulated in this Guideline, in order for the data to be deemed representative. Subsections 13(2) and 13(3) of Ontario Regulation 903 require that wells be constructed such that the casing of a drilled well protrudes at least 30 centimetres above ground surface or above the floor of a well pit. Well water contamination caused by the entry at the well head of water originating at or near the surface may occur if the well head is buried. Subsection 20(3) requires that the well owner maintain the well in a manner sufficient to prevent such contamination. Where well heads are buried, locating, inspecting and servicing the well are difficult and expensive. Page 40

21 Subsections 13(2), 13(3) and 20(3) are often contravened when, after a well is constructed, contractors or residents bury the well head for reasons of convenience or aesthetics. Contractors and residents should be reminded of the intent and requirements of these portions of the Regulation, and of their responsibility to ensure that the finished grade of the ground surface allows the casing to protrude the required distance. This is necessary to prevent ponding at the well head or, in the case of well pits, prevents flooding of the pit. Where flowing well conditions occur, the requirements of Regulation 903 must be met. The consultant must address these issues in the Preliminary Investigation Report and make the appropriate recommendations. The MOEE requires proper well construction and abandonment of any unused previously existing wells and/or test wells so that ground water contamination is prevented Adjacent Lands & Water Uses Land uses within a minimum of 500 metres of the site must be described. Where wells exist on or adjacent to the site, a survey of well owners, static and pumping levels and sampling and analysis of representative well water, should be performed and reported. Accessible off-site wells within 200 metres from any development well shall be monitored during the on-site pumping test. The potential for an adverse impact to or by the development must be addressed, when there have been, are, or may in the foreseeable future be significant potential sources of ground water contamination (e.g., from old, operating or proposed waste disposal sites, road salt storage facilities, farming activities, locations of contaminant spills, etc.), or potential causes of quantity interference with ground water resources or well water supplies (e.g., from municipal wells, dewatering activities, etc.) within a minimum of 500 metres of the site. The issue of whether additional water quality parameters should be included in the testing must also be addressed Other Considerations Shallow wells and unconfined aquifers are susceptible to seasonal fluctuations in water level. In these cases, the consultant must comment on the magnitude of such fluctuations and the effect on well yields and may need to perform additional investigations to determine the possibility of future well water quantity problems. Ground water heat pumps which do not return water to the aquifer of origin are not permitted. It is recommended that the consultant address the potential impact on water quality of the return of water from ground water heat pump systems to the aquifer of origin. (Provincial regulation and policy with respect to ground water heat pump systems is under development.) Typical treatment systems requiring "additional water" would be water softeners, iron filtration units, and reverse osmosis units. If treatment systems which require additional amounts of water for their operation are to be used, those rates must be added to the calculated minimum well yield. 4.3 HYDROGEOLOGICAL STUDY REPORT The well construction, test pumping and quality sampling procedures are similar to those described in the Preliminary Investigation Report, with the following modifications/exceptions: i) Provided that the well can be tested at the calculated peak demand rate discussed earlier in this guideline a Page 41

22 step test is not required on the well servicing the individual lot. ii) The well shall be continuously pumped for a minimum period of three hours if drawdown stabilization is observed during this test interval or otherwise the test should be continued for a minimum duration of six hours. Water levels must be monitored in the nearest on-site wells and in any accessible off-site well within a distance of 200 metres from the pumped well. iii) The well shall be developed to obtain a turbidity level not greater than five (5) NTU, being the concentration considered to be reasonably treatable by the MOEE (Part 5, Appendix A). iv) Water quality testing of the individual wells shall be undertaken on one sample collected near the termination of the pumping test and shall at least include: E. Coli and Total Coliform bacteriological determinations (on samples with zero chlorine residual) Iron, Manganese, Sodium Nitrate, Chloride, Sulphate Dissolved Organic Carbon Turbidity, Colour Hardness & Alkalinity v) Based on the observed drawdown and recoveries in the pumped wells and the private wells, the consultant shall confirm that adequate supplies of potable groundwater (with or without treatment) will be continuously available within the subdivision and the adjoining private properties. 4.4 ADDITIONAL INFORMATION It should be noted that the Region will not recommend approval for official plan amendments, draft plans of subdivision or condominium or other development plans, unless the Region is satisfied with the Preliminary Investigation Report. Where ground water of adequate quality and quantity is demonstrated to be available to service the proposed development, the Region will require, as a condition of final approval, that the development agreement between the municipality and the developer, include the recommendations of the Preliminary Investigation Report. If groundwater open loop heat pumps are being considered for use in the proposed development, an assessment must be included in the hydrogeological study to ensure that domestic potable water supplies will not be adversely impacted. If the issue of ground water heat pumps is not addressed in the report, the Region will request that a condition be placed in the development agreement indicating that the use of ground water heat pumps has not been approved as part of the development. The possibility of using systems to compensate for low well yields (for example, controlled pumping to supplementary storage) is discussed earlier in this guideline. If the Region agrees to their use, notification will be given through the development agreement between the municipality and the proponent(s). With respect to water quality, the following will apply (except for the 20 mg/l warning level for sodium): Page 42

23 - Where health and aesthetic ODWO criteria are met, the Region will comment favourably on approval of the Official Plan Amendment or on draft approval of the Plan Subdivision or Condominium. - Where health-related ODWO criteria are not met, the Region will recommend against approval of the proposal on the basis of individual wells. - Where health-related ODWO criteria are met but aesthetic objectives are exceeded, it may be possible to use in-home water treatment systems to reduce the values of the aesthetic parameter(s) concentrations to a level below the limits, and thereby meet the objectives. This guideline lists concentrations considered treatable for several aesthetic parameters and some possible treatment systems (Table 3, Part 5, Appendix A). If the Region agrees to the use of in-home treatment systems, notification will be given through the development agreement between the municipality and the proponent(s). The local municipality also shares responsibility for ensuring that the terms of the development agreement are carried out. PART 5 PRIVATE SEWAGE DISPOSAL SYSTEMS 5.1 INTRODUCTION Development applications which propose to employ on-site subsurface private sewage disposal systems will be required to include a terrain analysis and hydrogeological assessment to determine: a) the suitability of the site conditions for subsurface sewage systems and b) the potential on-site and off-site impacts on the ground water systems and surface water features. All proposed development on private services will be reviewed on the basis of being capable of supporting the installation of a conventional septic tank and tile bed system, maintaining an area of vacant and suitable land of at least 700 square metres. The purpose of the guideline is to protect the environment and public health by ensuring that development utilizing individual on-site sewage systems proceeds at a density and scale which will not result in, or cause degradation of, ground water resources in exceedance of acceptable limits. Compliance with acceptable limits shall be demonstrated through predictions of the development's nitrate impact on the ground water at the development boundary and at existing downgradient residences within 500 metres from the development. This guideline has been assembled with the recognition that each proposed development site has finite resources available to treat sewage, and that the resources are highly variable on the development site itself. Evaluation of the quality impact at the Preliminary Investigation should allow a realistic indication of the supportable development density before substantial costs are incurred by the proponent. This guideline applies to: Page 43