site suitability study: existing residential property 4845

Site Suitability Study:

Existing Residential Property4845 Bank StreetOttawa, Ontario

Prepared For:Ms. Patricia Rougier

March 18, 2015

Report No: FS-15-002-REP.01

Site Suitability StudyExisting Residential Development 485 Bank Street, Ottawa, Ontario

Report No: FS-15-002-REP.01Date of Issuance: March 18, 2014

TABLE OF CONTENTSPAGE

1.0 INTRODUCTION

1.1 Terms of Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Background and Property Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 METHOD OF STUDY

2.1 Terrain Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2 Topographic Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.0 HYDROGEOLOGICAL SITE CHARACTERIZATION

3.1 Surface Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2 Surficial Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.3 Bedrock Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.0 DEVELOPMENT RECOMMENDATIONS

4.1 General Development Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.2 Onsite Wastewater Treatment System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5.0 RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

APPENDICES

Appendix A Soil Profile and Test Data SheetsAppendix B Supporting DocumentationAppendix C Figures & Drawings

Figure 1 - Site Location PlanFigure 2 - Surficial Soils PlanFigure 3 - Regional Bedrock MappingDrawing No. FS15-002-1: Existing Conditions and Test Hole Location

Plan

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1.0 INTRODUCTION

1.1 Terms of Reference

Fieldstone Engineering Inc. (Fieldstone) was retained by Holzman Consultants Inc., on behalfof Ms. Patricia Rougier, property owner, to complete a site suitability assessment of the existingproperty located at 4845 Bank Street, former Township of Gloucester, Now City of Ottawa,Ontario, and hereafter referred to as the subject property. Reference should be made to theSite Location Plan - Figure 1, in Appendix C for site location information. It is ourunderstanding that this assessment forms part of a zoning by-law amendment application toallow for commercial use on the property.

Based on the available information provided by Holzman Consultants Inc., the subject propertyis designated “General Rura Area” in the City of Ottawa Official Plan and is presently zoned“Rural Countryside (RU)”. Furthermore, it is understood that a rezoning to Rural CommercialZone (RC) is being sought for the property

The purpose of this study has been to evaluate the existing property in terms of its potential to receive and attenuate sewage system effluent in the long term. As the site is presently servicedwith municipal water from the City of Ottawa, as are the adjacent properties in the immediatevicinity, the hydrogeological component of this assessment has not been completed.

These works have been completed in general accordance with the present City of Ottawaindustry standard which seeks to utilize the following Ontario Ministry of Environment (MOE)guidance documents in the completion of hydrogeological assessments:

• Guideline D-5: Planning for Sewage and Water Services(August 1996)

• Procedure D-5-4: Technical Guideline for Individual On-site SewageSystems: Water Quality Impact Risk Assessment (August1996)

The following report has been prepared specifically and solely for the aforementioned projectwhich is described herein. It contains our findings and recommendations pertaining to theprivate services for the subject development as it is understood at the time of writing this report.

1.2 Background and Property Description

The subject property presently consists of a two storey single family home with a circular graveldriveway and a wood clad garden shed. The single family home is presently serviced by amunicipal water supply connection and an onsite sewage system.

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The property is generally flat and has only a few trees scattered throughout the easternquadrant of the site, and along the south/east property limits. The site topography is consideredto be flat to gently sloping from west to east. A surficial cross-fall exists in the rear yard areathat moves surface water to the south, beyond the property line to a small, meandering,drainage ditch. Overall site drainage is considered to be imperfect to good.

Based on the existing plan of survey (refer to Appendix B (B1) for reference), Plan 4R-8862-prepared by Webster & Simmonds Surveying Ltd., Ontario Land Surveyors (OLS) datedJanuary 20, 1993, the subject property consists of Part 2 & Part 3 of the three lots. Part 1,located to the north of the subject property, has been developed as a single family residencealso.

The subject property, as noted in the preamble, is presently split serviced by municipal drinkingwater and an onsite wastewater treatment system. This form of servicing is generallyconsidered to be consistent with the established hierarchy prescribed in Section 1.6.6 of the2014 Ontario Provincial Policy Statement and is consistent with the established developmentwithin several designated rural sectors of the City of Ottawa. Examples of these rural sectorsoperating on split services include Orchard Estates, Merivale Gardens, and Britannia(Grandview Road).

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2.0 METHOD OF STUDY

2.1 Terrain Analysis

As part of the site suitability study, Fieldstone put down a series of hand auger holes across theproperty. The purpose of these test holes was to determine the composition and consistencyof upper one to two metres of the underlying overburden soils as they pertains to sewagesystem capacity.

A total of five (5)shallow auger holes were put down to a depth of between 0.9 m and 1.6 mbelow ground surface (bgs) in this area in January 2015. A summary of the stratigraphy for eachof the test holes is summarized in Appendix A and the locations of the test holes are providedon the Existing Conditions and Test Hole Location Plan - FS-15-002-1 located in Appendix C.

Based on an analysis of the test holes, the underlying surficial soils can be summarized asfollows:

Topsoil

Topsoil was encountered in each of the test holes. Topsoil thickness ranged from 150 mm tomore than 300 mm thick from west to east across the site. The eastern quadrant of the site,where the topsoil is the thickest, also contains a higher humic content consistent with theadjacent forested areas.

Silty Sand to Sandy Silt

A transitional soil, consisting of a tan brown to red-brown silty sand/sandy silt was observed tobe present beneath the topsoil layer in each of the test holes. The relative thickness of thistransition layer was noted to vary between 300 mm and 450 mm from the west to east acrossthe property. The silty sand/sandy silt layer was noted to have a compact consistency whereencountered in each of the test holes.

Silty Clay to Sandy Clay

A thin layer of silty clay was observed in all of the test holes. The silty clay was grey-brown incolour and was noted to have a firm to stiff consistency. The layer was noted to be saturated.

Bedrock

Refusal was noted in each of the test holes at a depth of between 500 mm and 950 mm belowground surface. Given the presence of frost across the site at the time of the field investigation,larger diameter holes could not be constructed to determine if the refusal was, in fact, bedrockor a very dense glacial till.

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Groundwater

An overburden water table was observed in TH3, TH4 and TH5 at depths of approximately 500to 750 mm below ground surface. The water table was present at, or slightly above the surfaceof the silty clay in each test hole, where encountered. Seasonal increases in the normal watertable are anticipated given the moderate permeability of the transition layer and the presenceof silty clay and bedrock beneath. As such, the slope of the water table is expected to followthe slope of the silty clay layer which, based on the observed depths, generally slopes fromwest to east/southeast across the property.

2.2 Topographical Survey

The ground surface elevations for the test well and the existing ground surface elevations werecollected by Fieldstone. The elevations appear on the Existing Conditions and Test HoleLocation Plan - Drawing No. FS15-002-1, located in Appendix C and have been overlayed onthe existing reference plan, on file with the Ontario Land Registry for the subject property. Theelevations are referenced to a relative benchmark only and, as such, the elevations noted onthe drawing are not intended to represent geodetic information.

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3.0 HYDROGEOLOGICAL SITE CHARACTERIZATION

3.1 Surface Conditions

The subject property consists, as noted in section 1.2, of a flat to gently sloping terrain withtopographic relief to the east/southeast. To the east, and south of the subject property, is adensely wooded area. A drainage ditch or water coarse flows through the lands to the south and appears to drain eastward from the roadside ditch running along Bank Street located tothe immediate west.

To the north, an existing single family residential dwelling has been constructed. Thefoundation of the house on the neighbouring property was noted to be raised significantlyabove that of the lands on the subject property and a retaining wall having a height ofapproximately 800 mm was constructed to abruptly adjust the grade at the northern propertyline. In an similar manner, the sewage system serving the neighbouring property to the northwas noted to be fully raised above the existing grade and the rear yard area slopes off gentlybeyond the leaching bed towards the east. Due to the presence of a thick layer of snowpresent at the time of the field investigation, the surficial drainage outlet for the neighbouringproperty could not be visually verified.

3.2 Surficial Geology

The surficial soils in the vicinity of the site generally consist of series of marine depositsassociated with the Champlain Sea overlying shallow bedrock. The available surficial soilsmapping provided by the Ontario Geologic Survey (OGS) is shown on the Surficial SoilsDelineation Plan - Figure 2, located in Appendix 5. The mapping indicates that the subjectproperty is located on a stone-poor silty sand to sandy silt till layer overlying Paleozoic bedrock. The mapping is considered to be consistent with the results of the field investigation.

Based on the site suitability evaluation completed on the in situ till material, the soil layer thatwill receive sewage system effluent will be the silty sand to sandy silt transition layer. Theconsistency of this layer was estimated to be compact to dense. An estimated saturatedhydraulic conductivity of the order of 10-4 cm/s has been placed on this material within theproposed leaching bed area. This hydraulic conductivity corresponds to a design percolationrate, or T-time as it is referred to in the Ontario Building Code (OBC) of 25 to 30 min/cm.

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3.3 Bedrock Geology

Published geological mapping provided by the Geologic Survey of Canada (2003), andcourtesy of Natural Resources Canada, reveals that the site, like all of the Village of Greelyarea, to be underlain by Paleozoic limestone. Specifically, the subject site is situated on topof March Formation with the Oxford Formation present immediately to the south of the site. Both the March Formation and the Oxford Formation are, historically, an excellent source ofbedrock aquifers, with an aquifer system present within both of these formations throughoutthe Greely area. Reference can be made to Figure 3- Regional Bedrock Mapping, located inAppendix C.

Generally, the Oxford Formation is underlain by dolostone-sandstone of the March Formation,which, in turn, is underlain by sandstone of the Nepean Formation of the Potsdam Group. Underlying the Potsdam Group is a series of granites of the Precambrian Group.

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4.0 DEVELOPMENT RECOMMENDATIONS

4.1 General Development Constraints

The site is located within an existing commercial/residential mixed use corridor located alongBank Street. If the property is re-zoned to permit commercial uses, there are only a fewdevelopment constraints for the site development other than those related to the OntarioBuilding Code and municipal zoning setbacks. Specifically, the following key constraints applyto this development:

• the existing residential dwelling, if it demolished, will require the decommissioning ofthe sewage system at the same time (refer to Section 4.2 for more information);

• the adjacent drainage ditch, located on the adjacent property, will require horizontalsetback to new/replacement sewage system components of at least 15 m (OBCrequirements) (zoning requirements may be 30 m depending on the interpretation of theexact nature of the drainage course);

• replacement septic tank/pretreatment tank/advanced treatment unit(s) must be locateda minium of 1.5 m from the building and 3.0 m minimum from the property line;

• given the shallow bedrock and variable water table present beneath the site, a fullyraised leaching bed will be required;

• available land area, depending on the nature of the commercial use, is expected to beat a premium. As such, advanced wastewater treatment technologies will likely benecessary.

4.2 Onsite Wastewater Treatment System

Existing Sewage System

As noted Section 1.2 of this report, the existing residence is serviced by an existing sewagesystem. Based on the available information provided by Ms. Rougier, the sewage systemconsists of a septic tank discharging primary quality effluent to an in ground absorption trenchleaching bed. Due to the thickness of the frost at the subject site, the existing conditions (ie.size, and general orientation of the sewage system components could not be established aspart of this assignment. Reference can be made to the Existing Conditions and Test HoleLocation Plan, Drawing No. FS-15-002-1, located in Appendix C for approximate locationinformation.

Based on the existing topgraphic information, it appears that the separation distance betweenthe underside of the absorption trenches and the limiting layer (silty clay/high groundwater tableand/or bedrock) is less than 900 mm. As such, if material alterations or repairs are proposedto the existing building which trigger a performance level reduction as per OBC requirements,or if the sewage system fails in the future in a continued use scenario, the leaching bed will berequired to be raised.

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Future Replacement Sewage System Considerations

As part of this study, Fieldstone has assessed the capacity of the existing lot to be serviced bya Class 4 sewage system at some future time. Based on present OBC requirements, andconsidering the surficial soils in the eastern quadrant, the subject property can be serviced bya sewage system using treatment equipment capable of producing tertiary quality effluent. Theeffluent can be dispersed into the natural environment using leaching bed design that receivestertiary quality effluent without significant impact to the receiving overburden water supplyaquifer.

The preferred location for a replacement leaching bed, based on the findings of theinvestigation and, considering Fieldstone’s expertise in onsite wastewater treatment anddispersal, is along the eastern quadrant of the property. Based on the available area locatedto the northeast, between the existing shed and the north property limits, an area ofapproximately 300 m2 is readily available. Conceptually, the soils in this area can receive andtreat a total daily design sanitary sewage flow of upwards of 4,000 L/day (based on a T-timeof 30 minutes/cm). This flow is considered to be in excess of typical design sanitary sewageflows for existing commercial uses in the vicinity of the subject property.

With respect to the existing sewage system components, in a redevelopment scenario, thesewage system components will be required to be decommissioned in accordance with OBCand provincial regulations. Specifically, the septic tank will be required to be emptied ofsanitary sewage and either removed from the site or crushed and left in place. The exact fateof the septic tank will depend on the exact location of the tank with respect to the proposedredevelopment site plan.

The decommissioning of the leaching bed will require either the complete removal of theleaching bed and upper 300 mm of the receiving soil from the site (alternatively stockpiled andattenuated over time), or the abandonment of the bed, in place, if the proposed redevelopmentsite plan does not propose a building envelope in that area. If onsite attenuation of thestockpiled aggregate and soil is chosen, the distribution piping should be removed andprocessed at a waste transfer facility and the remaining material should be covered with freshsoil cover to prevent attraction of vectors. An attenuation period of between 6 and 10 monthsshould be sufficient to remove all pathogenic bacteria from the material. The material can thenbe reused in landscaped areas, or removed from the site following successful confirmation ofattenuation by soil analysis.

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5.0 RECOMMENDATIONS

The following recommendations are derived from the combination of the findings of thispreliminary study, as well as the additional information requirements, identifiedthroughout the body of the report:

1. In a redevelopment scenario for commercial uses, the existing sewage systemcomponents should be properly decommissioned in accordance with OBCrequirements as part of the preliminary works.

2. All future new/replacement sewage systems should utilize wastewater treatmenttechnologies producing Level III or Level IV effluent quality as per Table8.6.2.2.A of the OBC.

3. Prior to redevelopment of the site, the area reserved for the sewage systemshould be protected against compaction, etc. resulting from construction relatedactivities. This will lead to unnecessary compaction and will reduce thepermeability of the receiving soil significantly increasing the size of the leachingbed.

The present report applies only to the project described in this document. Use of this reportfor purposes other than those described herein or by person(s) other than Ms. Rougier, or heragents is not authorized without review by Fieldstone for the applicability of ourrecommendations to the alternative use of the report.

Fieldstone Engineering Inc.

Robert A. Passmore, P.Eng.President

Report Distribution:

‘ Holzman Consultants Inc.(2 copies)G City of Ottawa (5 copies)‘ Fieldstone (1 copy)

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APPENDIX A

‘ SOIL PROFILE AND TEST DATA SHEETS

APPENDIX B

SUPPORTING DOCUMENTATION

B1:REFERENCE PLAN FOR SUBJECT PROPERTY

APPENDIX C

‘ FIGURE 1: SITE LOCATION PLAN

‘ FIGURE 2: SURFICIAL SOIL DELINEATION PLAN

‘ FIGURE 3: REGIONAL BEDROCK MAPPING

‘ DRAWING No.: FS15-002-1 - EXISTING CONDITIONS ANDTEST HOLE LOCATION PLAN

site suitability study: existing residential property 4845

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