.. I -_ '. i - '. I '. I. I I I I' i I I. .. ! .. .. I' 1 i -. I ! .. k. i PROVINCE OF NOVA SCOTIA DEPARTMENT OF MINES Groundwater Section Report 72 - 1 HYDROGEOLOGY OF THE TRURO AREA, NOVA SCOTIA I' '7 1;' I. TERRY W. HENNIGAR HON. GLENM. BAGNELL Minister J.P.NOWLAN, Ph. D. F.S. SHEA, M.Sc. > Deputy Minister Director Mineral Resources and Geological Services i Halifax, Nova Scotia 1972 I I PREFACE The Nova Scotia Department of Mines initiated in 1964 an extensive I programme to evaluate the groundwater resources of the Province of Nova Scotia. This report on the hydrogeology of the Truro area forms part of this broader pro- vincial programme. The field work for this study c om m e n c e d during the summer of 1965 when the Fraser Brook watershed was selected as the first representative basin for the study under the International Hydrological Decade programme in Nova Scotia. Detailed test drilling and mapping was carried out during the summer of 1967. The material for this report forms part of an M.Sc. thesis by Mr. T.W. Hennigar entitled Hydrogeology of the Salmon River and Adjacent Watersheds, Colchester County, Nova Scotia. The funding for this comprehensive project was a joint undertaking between the Canadian Department of Regional Economic Expansion (ARDA project No. 22042) and the Province of Nova Scotia. Use of the Dalhousie University's IBM/360-50 model computer was secured through the co-operation of the Department of Geology and was used in analysing some of the data contained in this report. It should be pointed out that many individuals and other government agencies co-operated in supplying much valuable in for m a t io n and assistance throughout the period of study. To list a few: Mr. F.S.Shea, M.Sc., Director Mineral Resources and Geological Services and the staff on the Mineral Resources section, Nova Scotia Deportment of Mines; the Nova Scotia Research Foundat- ion, and the Nova Scotia Agricultural College at Truro. It is hoped that the information in this report will be useful for agri- cultural, municipal and individual water needs and that the report will serve as a guide for the future exploration, development, use and management of the important groundwater resources of the Truro area. John F.Jones, P.Eng. Chief, Groundwater Section Nova Scotia Department of Mines _.------------- - Halifax, Nova Scotia :i? September,' 1972 CONTENTS Page Abstract .................................................... 1 Introduction ................................................. 2 Purpose and scope of investigation ....................... 2 General description of the area ......................... 2 Location. access. and extent of the area ........... 2 Land survey system .............................. 4 Physiography and drainage ....................... 4 Agricultural soil types ........................... 8 Engineering aspects of soils ...................... 10 Population and land use ......................... 11 CI imate ....................................... 11 Previous investigations ................................. 13 Field work and maps ................................... 15 Acknow Iedgements .................................... 16 Geology .................................................... 17 Introduction ........................................... 17 Rock units ............................................ 17 Cobequid Complex .............................. 17 Horton Grpup .................................. 20 Windsor Group ................................. 21 Canso Group ................................... 21 Riversdale Group ............................... 21 Pictou Group .................................. 22 Fundy Group ................................... 22 Surficial deposits ..................................... 23 Glacial till .................................... 23 Glaciofluvial deposits ........................... 26 Glaciolacustrine deposits ........................ 29 Peat and muck ................................. 30 Stream alluvium ................................ 30 Dykeland. salt marsh and tidal flats ............... 30 Buried channels ...................................... i 31 Structure ............................................. 32 . HydroI ogy .................................................. 33 Introduction .......................................... 33 Precipitation ......................................... 34 Precipitation at Truro and other establ ished instrument sites ................... 34 Salmon River water shed precipitation gauge network . 35 Determination of average precipitation on the water- shed ............................. 37 Evapotranspiration ..................................... 39 Stream flow .......................................... 43 Salmon River runoff ............................. 44 Fraser Brook runoff .............................. 48 Runoff .precipitation ratios ............................ 51 Groundwater hydrographs ............................... 52 Canso Group ................................... 52 Wolfville Formation ............................. 54 Surficial Materials .............................. 54 Hydrostratigraphic units ....................................... 59 Introduction .......................................... 59 Bedrock Hydrostratigraphic Units ........................ 60 Cobequid Complex .............................. 60 Horton Group .................................. 61 Windsor Group ................................. 62 Canso Group ................................... 63 Riversdale Group ............................... 63 ii .1 Pictou Group .................................. 63 Wolfville Formation ............................. 64 Surficial Hydrostratigraphic Units ........................ 65 Glaciofluvial deposits ........................... 65 Chemical Quality of Groundwater .............................. 67 Introduction .......................................... 67 Relationship of Groundwater Quality to Use .............. 70 Colour and Turbidity ............................ 70 Iron and manganese ............................ 71 Sodium and chloride ........................... 71 Nitrates ...................................... 73 %I phates ..................................... 73 Total hardness ................................ 74 Total dissolved solids ........................... 75 Chemical quality of groundwater in the hydrostratigaphic units .................................... 75 Introduction ................................... 75 Horton Group .................................. 76 3. I W indsor Group ................................. 76 Canso Group ................................... 76 Riversdale Group ............................... 77 =I 9z 1- zz 1 81 1 El 1 60 1 pol S33laN3ddV sa3 uaJaj ad 66 .................................................. suolsn13u03 puo XJDuunS 96 ...................................... E6 ......................................... OJnJl Jahla uoulDS Z6 ................................... 26 ........................................ UaPl!H 16 ........................................ wqaa 06 ..................................... PPU100J9 88 ..................................... I\!H aN!a 88 ***.*.*******.***.* salddns Ja+om p!J+snpu! puo Iod!3!unW sa! lddns Ja+OM UO!+D~!UI L8 ................................ sa! lddns ia+oM q~o+sah!I puo 3!+sauq S8 .................... .......................................... UO !+3npOJ+U I p8 ruaudolahap puo uo!+oz! I!+n P8 ................................... 18 ....................... Ja+DM a3ojJns jo X+!Ionb IO!Ja+3Og ***-* * * -.* -* ~a+oMa~opns jo 6L -- - Ionb 103!uay3 6L .......................................... U0!+3 npoJ+uI A+! pnb Ja+oM a3ojinS 6L ......................................... 8L .......................... s+!sodaa Io!AnIjopolf) u ............................. UO!lo~JOj I!AjIOM u .................................. dnojf) nop!d ILLUSTRATIONS Page Figure 1. Location of the study area and its physiographic units ......................................... 3 Figure 2. National topographic series showing Nova Scotia reference maps covering the area of study .......... 5 Figure 3. Watersheds within the immediate area of the Town of Truro ....................................... 7 Figure 4. Bedrock geology of the study area ................ 19 Figure 5. View of terrace development in Town of Truro with dykeland and Salmon River in background (view northeast) ..................................... 24 Figure 6. Granular till overlying the Cobequid complex. McCullam Settlement, 11 E 11 B 16 G (view east) ... 25 Figure 7. Remnants of ice-contact stratified drift on steep valley slope, North River, 11 E 6 C 72 Q (view east). ..... 26 w.. I Figure 8. Variations of bedding in kame, Greenfield, 11 E 6 A 102 P (view north) .............................. 27 Figure 9. Cross-section of esker, Archibald, 11 E 6 A 80 K (view south) ................................... 28 Figure 10. Outwash sand and gravel terrace, North River, 11 E 6 C 24 L (view east) ............................ 29 Figure 11. Mean monthly precipitation and evapotranspiration values in the study area ......................... 41 Figure 12. Mean monthly soil moisture surplus and deficit in the study area ..................................... 42 Figure 13. Discharge hydrographs of Salmon River at Murray for 1965 and 1966 ................................. 45 Figure 14. Discharge hydrographs of Salmon River at Murray for 1967 and 1968 ................................. 46 Figure 15. Discharge hydrograph of Salmon River