Aggregate Resource Potential of the Okanagan Area - Digital Data This file (legend.txt) details the methodology and procedures used in determining the aggregate resource potential of the Okanagan Area (NTS sheets 82E/3, 4, 5, 6, 11, 12, 13, 14, and 82L/3, 4, 5, 6, 11, 12, 13, 14). The 1:50,000-scale data are defined as Level III aggregate resource potential maps (Bobrowsky et al., 1996). The results are published in digital form only and should be cited as: P.T. Bobrowsky, PGeo, N.W.D. Massey, PGeo., and A. Matheson, PGeo. (1998); Aggregate Resource Potential of the Okanagan Area (NTS 82E(west) and 82L(west)), B.C. Ministry of Energy and Mines, Open File 1998-5 (digital data). Assessment of Aggregate Resource Potential Within the Okanagan area, 3400 individual areas (polygons) have been assessed for hosting potential natural aggregate resources. The polygons are based on soil and landform units identified and delineated by Kowall (1986) and Wittneben (1989), with additions and modifications by the authors. The potential has been assessed by compiling data for each of the original 3400 landform polygons. Each parameter contained several classes used to rank polygons (see table below and Bobrowsky et al., 1996). Data for factors and rankings have been included as attributes for the landform polygons in the digital files. Geological Factors The factors used to assess the potential of a polygon to host aggregate are: 1) Landform type: aggregate deposits occur in certain favourable environments which can be interpreted from the observable landforms. The ranking was assigned for both major (Geol1) and secondary (Geol2) landform designations within an area (rankings - G1_rank and G2_rank). 2) Texture of soil type: The soil association developed upon a landform has been rated by Kowall (1986) for the proportion of gravel-sized (>2mm) particles. Similar ratings were determined for other polygons. Rankings were assigned for both dominant (Texture1) and secondary (Texture2) soil associations (rankings - T1_rank, T2_rank). 3) Area: the areas of non-water landform polygons range from 0.07 to 4485.9 ha (Area). They have been ranked (Area_rank) such that roughly equal numbers of landform polygons fall within each group. No allowance has been taken for partial polygons that occur at the edges of the project area. 4) Pits: each polygon was ranked for the presence or absence of aggregate pits within it (Pit_rank). No importance was attached to actual numbers of pits within a polygon (Pits). 5) Overburden thickness: The thickness of overburden which must be removed before extraction of aggregate can occur, is an important factor in evaluating the economic importance of a potential deposit. Data are derived from drill logs for water wells (data - Overburd; rankings - Over_rank) 6) Gravel Thickness and Volume: Where gravel is known to occur, the amount of gravel is important for determining economic value. However, very few volume estimates are available within the area, but thickness can be a useful alternative. Two databases yielded information: i) Field inspection of existing aggregate pits (data - Thick_pit and Vol_pit; rankings - Thp_rank and Vol_rank respectively). ii) Drill logs for water wells (data - Gravel _thi; rankings - Thick_rank) **********Final Rankings The final ranking of the landform polygons was achieved in a three-step process. First, all polygons (220) which host present or historical aggregate pits were separated out and assigned a classification "H". These represent 9.95% of the total area. Second, unfavourable polygons were eliminated based on the rankings for those parameters considered most important for indicating aggregate resource potential. Retained were those polygons with values of greater than 2 for g1_rank or g2_rank or thick_rank; or values of 5 for t1_rank or t2_rank. From this subgroup, those polygons with over_rank equal to 1 were eliminated. Eliminated polygons (1085) are classified "U" (Unclassified). They comprise 33.78% of the total area. Third, the retained polygons (2095), deemed most favourable to host undiscovered aggregate deposits, were subdivided into three categories based on the weighted final rank score: Total Rank = 3*g1_rank + 3*g2_rank + 3*thick_rank + 2*over_rank + 3*pit_rank + area_rank + vol_rank Values for the polygons ranged from 13 - 53. The significance of a polygon for aggregate resources was assigned: Primary potential (class=1): Total Rank > 30 Secondary potential (class=2): Total Rank 21 - 30 Tertiary potential (class=3): Total Rank < 21 For the whole project area, 274 polygons are of primary, 552 of secondary and 1296 of tertiary potential. These comprise 5.58%, 16.54% and 34.16%, respectively, of the total map area. Table 1: Summary of values used to determine rankings of individual parameters Ranking Geol Texture Area Pit (ha) 5 Glaciofluvial High >679 - 4 Fluvial Mod-high 398 - 679 - Variable 3 Ablation Till Moderate 238.6 - 398 - Colluvium 2 Eolian Low-mod 132.3 - 238.6 - Moraine 1 Glaciolacustrine Low <132.2 present Bedrock Organic 0 Water Unknown (all water absent Urban Areas polygons) Ranking Overburden Thickness Thickness Volume (Well) (Pit) (Well) (Pit) 5 0 - 1 m >10 m >27m >1,000,000 m3 (0 - 3') (>87') 4 1 - 2 m 8 - 9 m 17 - 27 m 500,000 - (4 - 6') (56 - 87') 1,000,000 m3 3 2 - 5 m 6 - 7 m 10 - 17 m 50,000 - (7 - 16') (34 - 55') 500,000 m3 2 5 - 10 m 4 - 5 m 5 - 10 m 5,000 - (17 - 33') (16 - 33') 50,000 m3 1 >10 m 2 - 3 m 0 - 5 m 0 - 5,000 m3 (>33') (0 - 15') 0 unknown 0 - 1 m unknown unknown Notes: Aggregate resource potential maps provide guidelines for testing, evaluating and managing aggregate resources within a defined area. The maps are intended to provide first approximation estimates of broad, regional aggregate distribution. Areas are ranked for their potential to host natural aggregate deposits (mainly gravel). Neither sand deposits nor crushed rock were considered. Detailed groundwork, including mapping, drilling and geotechnical evaluation, is required to further locate, outline and estimate the quantity and quality of the deposit before its economic significance can be evaluated. Rankings, both for individual parameters and final total ranking, are relative between areas within the project and cannot be compared directly to results from other study areas. All data were used as presented by the agency responsible for a particular database. The accuracy and integrity of those data are assumed. The authors and the Geological Survey Branch are not responsible for inaccuracies, omissions and errors resulting from this work. Sources of Information: Soils and landforms: Kowall, R. 1986a; Soils of the Penticton Map Area 82E, Ministry of Environment, Lands and Parks, Maps, scale 1:50,000. Sheets: 82E/03 Osoyoos 82E/04 Keremeos 82E/05 Penticton 82E/06 Beaverdell 82E/11 Wilkinson Creek 82E/12 Summerland 82E/13 Peachland 82E/14 Kelowna Kowall, R. 1986b; Soils of the Vernon Map Area 82L, Ministry of Environment, Lands and Parks, Maps, scale 1:50,000. Sheets: 82L/03 Oyama 82L/04 Short's Creek 82L/05 Westwold 82L/06 Vernon 82L/11 Salmon Arm 82L/12 Monte Creek 82L/13 Chase 82L/14 Sorrento Wittneben, U. 1989; Surficial Materials, Okanagan and Similkameen Valleys, Ministry of Environment, Lands and Parks, Maps, scale 1:20,000. Sheets: 82E 002, 003, 011, 012, 021, 022, 023, 031, 032, 033, 042, 043, 052, 053, 062, 063, 072, 073, 082, 083, 084, 093, 094 82L 003, 004, 013, 014, 023, 024, 025, 034, 035, 044, 045, 054, 055, 064 Water well data: Water Management Division, Ministry of Environment, Lands and Parks, Victoria. (enquiries phone: 250-387-9483 or via Internet at http://wtrwww.env.gov.bc.ca/wat/gws/gwis.html) Other references: Bobrowsky, P.T., Massey, N.W.D. and Matysek, P.F. 1996; Aggregate Forum, Developing an Inventory that Works for You!, Report of Proceedings, Ministry of Energy, Mines and Petroleum Resources, Information Circular 1996-6. Matheson A., MacDougall, D., Bobrowsky, P.T. and Massey, N.W.D. 1997; Okanagan Aggregate Potential Project, in Geological Fieldwork 1996, Lefebure, D.V., McMillan, W.J. and McArthur, J.G., Editors, British Columbia Ministry of Employment and Investment, Paper 1997-1, pages 347 - 352. Matheson A., Paulen, R., Bobrowsky, P.T. and Massey, N.W.D. 1998; Okanagan Aggregate Potential Project, in Geological Fieldwork 1997, British Columbia Ministry of Employment and Investment, Paper 1998-1, page 29a-1.