61 Chapter 4 Physical Setting Introduction The physical setting is a description of the land on which the property is located. The physical characteristics are relied on to assist in the speculation as to the potential for migration of contaminants to the groundwater and soils within surrounding areas. The level of diligence in an investigation should be escalated where migra‑ tion potential of a contaminant to a major aquifer is signicant. A site may have soils that conne and prevent migration of hazardous substances. The closest drinking water source is a private well outside a 1‑mile radius, and the water source is 400 feet down with a layer of impermeable, unfractured slate (at rock) as a barrier. The concern for a site such as this is not as great as one involving a property that is directly over a recharge zone to a major aquifer where surface contaminants may easily migrate to the groundwater. The information contained within this chapter provides the reader with the basic concepts for understanding the relationship between a physical set‑ ting and its impact on the spread potential of hazardous substances. Hazard‑ ous substances may spread through soil or rock formations, surface water, groundwater, and air. If you require a more in‑depth understanding of the soils and ground‑ water, consult a geologist or hydrogeologist. For instance, if the investigator determines that there is probable soil co ntamination on an adjacent prop ‑ erty that could result in a costly impact to the property being evaluated, the investigator may seek add itional expertise. A possible problem has been identied, and the soil is highly variable, so it is difcult to predict migra‑ tory ow. Then, a geologist or hydrogeologist could project the probability for that contaminant to migrate to where it could have a detrimental effect on the property and its immediate environment. Environmental factors include the relative location (geography), land con‑ touring (topography), geological characteristics (surface soils and subsurface geology), surface water characteristics (hydrology), subsurface water and soil characteristics (hydrogeology), and ood plain inuences. All are a basis for potential impact on the migration potential of hazardous substance contami‑ nation in a given environment. The only thing required by the ASTM Standard, and mandated by the All Appropriate Inquiries Rule, is a current topographic map. One or more addi‑ tional sources of physical information are discretionary. The discretionary 7966.indb 61 10/19/07 6:49:11 AM © 2008 by Taylor & Francis Group, LLC 62 Environmental Site Assessment Phase I physical setting sources should be sought: (1) when conditions have been identied to indicate that hazardous substances or petroleum products are likely to migrate to the property or from the property via the soil or ground‑ water; and (2) in order to assess the probable impact of known contaminants and project the direction of migration. Geographic Description The relative location of the property provides information concerning proxim‑ ity to population centers. Numerous sources can provide geographic maps. Each state Department of Highways has a complete set that covers the entire state, including rural areas. Each city Chamber of Commerce has maps that cover their city and some of the surrounding areas. Commercial street directories (e.g., Rand McNally Street Direction Finders), which can be purchased wherever maps are sold, are available for large population centers and the surrounding areas (e.g., Dallas Metroplex). All can be purchased for a nominal fee, and those that contain block numbers will prove useful later when you are plotting locations associated with the property. A parcel of land is not an isolated entity. Its relative associations and activ‑ ities may impact or be impacted by other properties. For instance, raw land located adjacent to an industrial complex may be impacted by the others’ environmental pollutants. Likewise, an industrial activity located 10 miles from the nearest resi‑ dence is unlikely to either be affected by or affect the other. On the other hand, an industrial site may be near a water reservoir that the neighboring community relies on for drinking water. Poorly managed hazardous wastes could end up in the reservoir due to its proximity. Topographic Characteristics Topography is land contouring information, a delineation of relative eleva‑ tions of land surfaces. Knowledge of the ground topography may be used to predict directional movement of soil contaminants. If the soil is known to be contaminated in a given area, migration potential to other areas will be affected by ground contours, which inuence the direction of ow. Maps are prepared by the U.S. Geological Survey and can be obtained from them, the city planning department, and retail stores. The most com‑ monly used map is the U.S. Geological 7.5‑Minute Series. The minutes refer to the scale; thus, a 7.5‑minute series spans 7.5 minutes of longitude and 7.5 minutes of latitude and is on a scale of 1:24,000, 1 inch to 2,000 feet. As can be observed in Figure 4.1, the most prominent information is the depiction of elevation levels, within contour lines. Rivers and lakes are delineated on these maps, as are some major population centers, roads, marine shoreline features, mines, and caves. However, the information does not stop with 7966.indb 62 10/19/07 6:49:11 AM © 2008 by Taylor & Francis Group, LLC Physical Setting 63 topographic features. There is more that could be helpful when identifying other land features. Probable pathways and direction of ow of soil contaminants are impacted by the rise and fall of the land. Although the ground formations below the surface do not always lend themselves to the same contours as that which is observed on the surface, the surface and subsurface contours are generally similar. Geologists can further interpret topographic maps with their knowl‑ edge of how the earth is formed. It should be noted that topography changes over time due to the forces of nature, mining, landll activities, and development of articial lakes. Figure 4.1 Topographic maps of Key Largo, Florida, depicting ground elevations and land usage changes over time, showing golf course, sewage disposal, airport, buildings, and roads. Continued . Mapped in 1949 7966.indb 63 10/19/07 6:49:13 AM © 2008 by Taylor & Francis Group, LLC 64 Environmental Site Assessment Phase I Topographic maps are, thus, updated when these changes are known and sufcient money is available to contract for the updates. In some instances, updates may be as frequent as every ve to ten years, but some are as much as fty years old. The old topographic maps are generally sold prior to the more dated maps if an investigator does not know to request the latest version. All the maps have the data accumulation date on them. Check the dates. Surface Soils and Subsurface Geologic Characteristics 1 Surface soils are the top layer of the earth’s surface, and geology involves the interpretation of soils and rock near the earth’s surface. Information concerning Mapped in 1973 Figure 4.1 Continued. 7966.indb 64 10/19/07 6:49:16 AM © 2008 by Taylor & Francis Group, LLC Physical Setting 65 surface soils and subsurface geologic formations is used to determine the poten‑ tial for contaminant migration, once again providing the investigator a means by which to predict the movement and environmental impact of contaminants. Surface Soils Surface soil information may be obtained from the U.S. Department of Agri‑ culture or the county soil conservation service. The U.S. Department of Agri‑ culture publishes information about the suitability of identied areas for general land use. Data includes the types of soil; steepness of slopes; drainage information; soil pH; depth to bedrock; and anticipated native vegetation. Each document, published by county, has a series of soil maps, presented on aerial photographs, in the back of each manual. The scale is 1:24,000, and the maps are marked to denote soil types, as depicted in Figure 4.2. Other designated markings include man ‑made features (e.g., roads, railroads, and pipelines), water features (e.g., wet spots, rivers, and lakes), and other perti‑ nent information (e.g., rock outcroppings, gullies, and dumps). Table 4.1 con ‑ tains a more detailed list of features provided on these maps. Permeability serves as an indicator regarding the accessibility of rainwater or surface water and associated contaminants to the subsurface ge ologic for ‑ mations. Permeability is measured in inches per hour and is based on water’s ability to migrate downward through saturated soil. Permeability rates range from very slow, less than 0.06 inches per hour (e.g., certain types of clay), to very rapid, greater than 20 inches per hour (e.g., sandy soil). See Table 4.2 for a relative description of the permeability rates. If there is no potential for con‑ taminants, the point is moot, and the soil type provides nothing more than land usability information. However, if a potential for contaminants does exist, the soil permeability is relevant. For instance, if there is an oil renery on a site where the soil permeability is 20 inches per hour, the threat of a chemical contaminant migrating downward is highly probable. Slope steepness is provided in degrees for each soil type. Sloping infor‑ mation gives the potential direction of ow and migration, not only through the soil, but over the uppermost surface. A 30‑degree slope poses a greater possibility for migration downhill than a 2‑degree slope. Drainage information is qualied by soil type and subtype. This is gen‑ erally part of the written description and merely states extent of drainage, ranging from excessively drained (i.e., water is removed from the soil very rapidly) to very poorly drained (i.e., water is removed so slowly that free water remains at or on the surface during most of the growing season). Soil pH information is found in the soil tables. This information may be useful where there are underground storage tanks or waste drums. Con‑ tainer deterioration is attributed to corrosive soils and other environmental contacts. A soil type that has a pH between 6.6 and 7.3 is neutral. The lower the pH, the stronger the acidity. The higher the pH, the stronger the alkalin‑ ity. Both extremes may have an impact on steel. 7966.indb 65 10/19/07 6:49:16 AM © 2008 by Taylor & Francis Group, LLC 66 Environmental Site Assessment Phase I Depth to bedrock is found in the soil tables as well. This is the depth of the soils and other unconsolidated material before it reaches the under‑ lying rock. Keep in mind that some bedrock extends to the surface and fails to support soils (e.g., Enchanted Rock, Texas). Thus, surface bedrock is not affected by soil data whereas soil data will affect the migration potential down to bedrock. Native vegetation information, rarely used by investigators, is difcult to interpret if one is not familiar with native plants. Yet, where it is known that grasses and trees normally occupy the landscape and the land is void of Figure 4.2 Soil survey map of area north of Georgetown, Texas, depicting soil types, municipal airport, quarries, roads, and buildings. 7966.indb 66 10/19/07 6:49:19 AM © 2008 by Taylor & Francis Group, LLC Physical Setting 67 Table 4.1 Features Depicted on Soil and Topographic Maps Land Features U.S. Soil Survey Maps USGS Topographic Maps Contours Soil type X — Elevations — X Land features — X Coastal features — X Mines and caves Mine dump — X Pits X X Quarry X X Tailings — X Parks X X Oil/gas pipelines X X Power transmission lines X X Railroads X X Roads & highways X X Structures Aboveground tanks X X Airports X X Cemeteries X X Dams X X Dumps — X Fence lines Occasionally X Oil/gas wells X X Pits X X Water wells X X Windmills X X Submerged areas Gully X — Swamp/marsh X X Vegetation — X Water features Lakes, ponds, and reservoirs X X Marine shorelines — X Note: Partial extraction from the respective map legends. 7966.indb 67 10/19/07 6:49:19 AM © 2008 by Taylor & Francis Group, LLC 68 Environmental Site Assessment Phase I vegetation, this may be a ready clue that vegetation has died or is unable to grow, likely due to contaminated soil. Subsurface Geology Subsurface geology refers to the formation characteristics of an area that is below the surface soil or directly exposed at the surface and precedes or con‑ tains groundwater. Information regarding subsurface geology is provided on U.S. Geological Survey maps. They may be purchased or can even be found in some university libraries. Characteristics of interest are rock types—permeability and thickness. This information should assist the investigator in determining the ground ‑ water susceptibility to contamination through the bedrock. An aquifer located beneath impermeable layers of rock and clay is less susceptible to surface contaminants than one located beneath fractured rock and sand. The geologic maps are typically on a scale of 1:250,000 and encompass part of or all of several counties. See Figure 4.3 for an example of the geologic atlas of the area around Texas A&M University. Each set has an index with the area of coverage delineated in a rectangle or square. The formations, indicated on a map, are detailed within an explanatory book enclosed with each map. An example of explanatory information follows: Catahoula Formation [Mc]: Clay and sand; clay, benton‑ itic, noncalcareous except for some calcareous concretions locally, light olive gray; sand, tuffaceous, ne to medium grained, crossbedded lenses, light gray to grayish brown; thickness 120–300 feet, thins southwestward. This information may require the assistance of a geologist to ascertain per‑ meability of the various layers. Surface Water Hydrologic Characteristics Hydrology is the study of the occurrence, movement, and quality of water above, on, and beneath the earth’s surface. Surface water is another mode for transporting hazardous substances from one site to another. When the rate of Table 4.2 Permeability of Soils Very slow Less than 0.06 in./hr Slow 0.2 to 0.6 in./hr Moderate 0.6 to 2.0 in./hr Moderately rapid 2.0 to 6.0 in./hr Rapid 6.0 to 20 in./hr 7966.indb 68 10/19/07 6:49:20 AM © 2008 by Taylor & Francis Group, LLC Physical Setting 69 precipitation exceeds the rate of soil inltration, overland ow occurs. Excesses also percolate downward to the groundwater, then laterally to sites of ground‑ water discharge, feeding into the surface waters. See Table 4.3 for relative avail‑ able freshwater content of the earth’s surface and Figure 4.4 for a depiction of the impact of the hydrologic cycle on the spread of contaminants. Figure 4.3 Geologic atlas of area around Texas A&M University, College Station, Texas, depicting geologic formations, airports, roads, and railroads. (Source: Bureau of Economic Geology, The University of Texas at Austin, 1974.) 7966.indb 69 10/19/07 6:49:23 AM © 2008 by Taylor & Francis Group, LLC 70 Environmental Site Assessment Phase I Surface water includes lakes, rivers, ponds, creek beds, and streams. Lakes and rivers may be located on the soil survey maps and other maps of the area (e.g., street and topographic maps). Ponds, creek beds, and streams are sometimes identied on topographic maps, but they will most likely require visual conrmation. Conrmation may be through an on‑site visit or by aerial photographs. Most lakes are man‑made. They have been installed with a sp ecic purpose in mind. Although most are intended for recreation, some are used as a water reservoir for a community. In the latter case, boating may not be allowed. Table 4.3 Freshwater Volume from the Hydrosphere Ice sheets and glaciers 5,800,000 mi 85% Groundwater 960,000 mi 14% Lakes and reservoirs 37,000 mi 0.5% Soil moisture 20,000 mi 0.3% Vapors in the atmosphere 3,400 mi <0.1 River water 300 mi <0.1 Source: Heath, Ralph C.: Basic Ground‑Water Hydrology. U.S. Geological Survey, Water‑Supply Paper 2220, p. G‑3. City Shale Confining Layer Sand and Gravel Aquifer Water Table Septic Tank Underground Storage Tank Wellhead Protection Area Contaminant Migration River Landfills Industrial Impoundments Urban Runoff Acid Rain Recharge to Groundwater & Surface Water Abandoned Well Manure Piles Pesticides & Fertilizers Groundwater Flow Municipal Water Supply Gasoline Service Station Groundwater Flow Hazardous Waste Dumpsite Figure 4.4 Hydrologic impact on the spread of contaminants. Environmental con‑ tamination is under stricter controls in the “wellhead protection areas.” (Source: Texas Water Commission: A Wellhead Protection Area. Austin, Texas, July 1990, pp. 6–7.) 7966.indb 70 10/19/07 6:49:25 AM © 2008 by Taylor & Francis Group, LLC [...]... 48 4 6 Kce 721 1 74. 60 126.37 Feb 4, 1 940 Nov 18, 1958 N N Well D- 148 in 1957 Travis County report 2 /4/ 2 04 R R Sansom Albert Neans 750 Kce 6 94 152.76 151.05 June 4, 1 940 Aug 4, 1 948 N N Well D- 144 in 1957 Travis County report 2 /4/ 103 B F Payton B F Payton 1 940 1 ,45 6 6 46 0 Kce 633 N N Well E -4 1 in 1957 Travis County report 2/3 /4/ C J Graves 1 941 41 30 41 Kgn, Kgt 615 21.18 56.70 28.80 24. 10... 24 hours at 300 gal/ min on Apr 28, 1962 3/ Dug well Well H-18 in 1957 Travis County report 4/ Seiders Springs Discharge: Sept 4, 1971, 150 gal/min; June 7, 1 942 , 30 gal/min Walling Estate 44 2 5 Kce 718 40 2 J C Campbell, Jr * 40 3 Texas Department of Public Safety * 40 4 * 40 5 * 501 135.06 1 24. 60 181.79 182.61 Flows N Oct 17, 1 940 Apr 15, 1953 C, W S Well H- 24 in 1957 Travis County report 2 /4/ ... gal/ min on Feb 16, 1973 395 5 248 Kce 733 C, W D Show of oil in the Edwards Limestone Well D-133 in 1957 Travis County report 3 /4 Spring Kce 740 Flows P Estimated yield 10 gal/min on Feb 9, 19 74 40 0 6 150 Kce 6 74 93.80 Oct 17, 1 940 C, G D, S Well D- 149 in 1957 Travis County report 4/ Method of lift Use of water Remarks Travis County—Continued * YD-5 8 -4 3-1 05 City of Austin * 106 W F Robinson... 10/19/07 6 :49 :37 AM 7966.indb 80 80 Sattler R AU Y ER U LN RY ER CH R VE NO HA 48 546 30090C H E UP RO C KY TO P RA AL AD GU IT MM SU 10/19/07 6 :49 :38 AM Figure 4. 10 Web site publication of existing and proposed 100-year flood zones Area in Comal County that had flooding above the flood zones in 1998 and 2002 © 2008 by Taylor & Francis Group, LLC Environmental Site Assessment Phase I OW NR CA PE 48 546 30085C... 10/19/07 6 :49 :33 AM 78 Environmental Site Assessment Phase I 575 ZONE A4 4 57 Creek RM 4 8-0 5 NE B ZONE B 3 57 ZONE C 583 58 5 ZONE B 588 Cr eek 1 58 ZONE B ZONE A10 59 ZONE B 0 ZONE B Cr k ee 59 2 Figure 4. 8 A 100‑year floodplain map (flood insurance rate map), depicting Zone A (areas of 100-year flood), Zone B (100-year to 500-year flood), quarry, airport, roads, buildings, and flood elevations ©... Hospital 1963 Elmo Miertschin 40 1 27 G B Heath * 1971 33 6 33 Kgn, Kgt 540 J, E Irr 1895 1,975 Kcho 635 15 Sept 1 941 N N Hugh McGillvray 27 36 -Destroyed Reported flow 1 04 gal/min when drilled Stopped flowing in 1938 Well H-19 in 1957 Travis County report 3 /4/ 5/ 1 84 10 Kgac 675 Oct 17, 1 940 Dec 6, 1950 C, W N Well H-22 in 1957 Travis County report 2 /4/ Texas Water Wells, Incorporated... E 48 091C0260F R VE NO HA 48 546 30085C E UP 48 546 30090C RO C KY TO P RA AL AD GU H OW NR CA PE RY ER CH Mapped in 2002 Y ER LE AL TV U LN NC TR WA UN RR E RIV ES RIV H AC PE Y P LE R AU L VA DG E LAT E AT RG E RIV IN TA UN RE FO ER EM ST MO D AL MARKET HTS R LE TT SA Sattler IT MM SU © 2008 by Taylor & Francis Group, LLC 81 10/19/07 6 :49 :39 AM Figure 4. 10 Continued 82 Environmental Site Assessment Phase. .. 633 N N Well E -4 1 in 1957 Travis County report 2/3 /4/ C J Graves 1 941 41 30 41 Kgn, Kgt 615 21.18 56.70 28.80 24. 10 July 24, 1 941 Mar 14, 1978 3 04 June 23, 1950 Dec 28 1972 N N Dug well Well E-51 in 1957 Travis County report 4/ * 305 C R Anderson 1920 22 36 22 Kgn, Kgt 640 4. 10 Apr 12, 1972 J, E D Dug well 306 R E Joseph 23 36 23 Kgn, Kgt 625 18.80 do Cf, G S Do * 307 John Wilder 23 36 23... report 2 /4/ © 2008 by Taylor & Francis Group, LLC 73 10/19/07 6 :49 :27 AM Figure 4. 5 Table of groundwater depths (Source: Texas Department of Water Resources: Occurrence, Availability, and Quality of Ground Water in Travis County, Texas Austin, Texas, Report 276, June 1983, p 131.) 74 Environmental Site Assessment Phase I water to thousands of people are of greater concern than a small pocket of water... Agency Flood Map Distribution Center 6930 (A-F) San Tomas Road Baltimore, MD 21227‑6227 Maps may also be obtained from city planning departments More recent FEMA proposed updates are available on the FEMA Web site and sometimes on county Web sites County Web sites may have additional area flood infor‑ mation as well (See Figures 4. 9 and 4. 10.) Influences and Relationships The primary concern in determining . Well D-133 in 1957 Travis County report. 3 /4 Estimated yield 10 gal/min on Feb. 9, 19 74. Well D- 149 in 1957 Travis County report. 4/ Well D- 148 in 1957 Travis County report. 2 /4/ Well D- 144 in. 93.80 1 74. 60 126.37 152.76 151.05 21.18 56.70 28.80 24. 10 4. 10 18.80 20.10 25.10 15 135.06 1 24. 60 63 12.00 181.79 182.61 Date of measurement Oct. 17, 1 940 Feb. 4, 1 940 Nov. 18, 1958 June 4, 1 940 Aug. 4, 1 948 July 24, 1 941 Mar. 14, 1978 June 23, 1950 Dec Wells, Incorporated Date Completed 1927 1 940 1 941 1920 1963 1971 1895 1962 1920 Depth of well (ft) Spring 395 Spring 40 0 48 4 750 1 ,45 6 41 22 23 23 27 33 1,975 1 84 353 27 Spring 44 2 Casing Diam- eter (in.) Depth (ft) 5 6 6 6 30 36 36 36 36 6 10 10 5