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Principles of site evaluation _adapted in part from Arnold et al by malj


									 1                               Principles of Site Evaluation

 2                      David L. Lindbo, Randy Miles, DeAnn Presley

 3                                        ABSTRACT

 4          Site evaluation is needed for virtually all projects that are related to land

 5   use planning or land management. Often this may appear overwhelming. This

 6   paper presents a logical, sequential approach to site evaluation that can be

 7   applied to many projected land use plans or land management goals. The

 8   process is broken into 3 basic activities; 1) collection of preliminary materials, 2)

 9   collection of field data, and 3) development of a final report. Each of these

10   activities is further broken down into subtasks. In order to perform the site

11   evaluation the practitioner needs to have a firm grasp on several things. First,

12   the needs of the client must be clear. Next, an understanding of any rules and

13   regulations that are applicable to the project must be apparent. This includes

14   acquiring background information on best management practices (BMPs) and

15   potential technological solutions relevant to the proposed future land use.

16   Knowledge of how to perform field evaluations is also essential at this point.

17   Finally, the practitioner needs to be able to communicate the findings back to the

18   client in terms the client and regulators can understand. Together these steps

19   provide a framework for site evaluation and facilitate communication between the

20   client and practitioner.


22                                     INTRODUCTION

23          One of the keys to any land use planning decision or best management

24   practice implementation is a site evaluation. The evaluation determines site

25   suitability for any given land use and points out site limitations. Only after a site

26   evaluation has been completed can land use options for the site be adequately

27   identified. The purpose of the site assessment is to characterize the soil,

28   hydrology, and landscape of the site; to predict water flow over and through the

29   soil and into subsurface materials, as well as to provide basic information for

30   specific use BMPs based on the intended land use (Arnold et al., 1996; Lindbo et

31   al., 2005; Trotta et al., 2005). A comprehensive site evaluation requires

32   considerable and diverse expertise by a soil scientist. The soil scientist must

33   have substantial knowledge about soil science, geology, agronomy, hydrology,

34   and applicable local, state, and federal codes, rules and regulations. A

35   systematic sequential approach to site evaluation was originally developed by

36   Arnold et al. (1996) specifically for on site wastewater applications. This chapter

37   modifies and expands that approach so that it applies to other applications.

38          There are 3 basic actions that are performed in order to adequately

39   evaluate a site: 1) Collection of preliminary information, 2) field evaluation,

40   testing, and/or monitoring, and 3) developing a final report. Within each of these

41   actions several sequential steps need to be performed to adequately evaluate

42   the site.

43                                 MATERIALS AND METHODS

44                            Collecting preliminary information

45   Establish client intentions

46           The old adage “prior previous planning prevents poor performance” should

47   be taken to heart during this stage of the project. The first step in conducting a

48   soil and site evaluation is to understand the owner’s or developer’s objectives

49   and expectations. The client should first explain in detail 1) what the intended

50   use of the site is planned to be, 2) preferences on specific land use locations

51   such as building, roads, constructed water features etc., and 3) future plans for

52   expansion or alternative land uses. At this point a clear understanding of the

53   project scale is developed. The scale will allow the site evaluator to determine

54   the appropriate level of detail need to complete the project, develop a time line

55   for project completion, and a estimated cost for the site evaluation (i.e., a project

56   bid).

57           It is incumbent that the consultant gets a clear delineation of the client’s

58   land use values and subsequent objectives. This full explanation is critical for the

59   consultant to obtain so that the objectives of the developments are fully

60   expressed. The next steps will go more smoothly if the first step is well-stated

61   and expressed. If the original objectives are not clear and concise the efficiency

62   of the project will be decreased. Additionally, frustration on the part of the client

63   and evaluator could be heightened.


65   Determine the regulatory framework

66           Once the framework of the intended site use is established, it will then

67   become important to acquire information about the land use indicated by the

68   client in the next step. The consultant needs to become familiar with all the

69   pertinent local, county, state, and federal rules and regulations that apply to the

70   site. It is imperative the consultant has a good understanding of the rules and

71   regulations in any particular jurisdiction in which he/she is working. Furthermore,

72   it is better to involve the regulatory authorities early in the process to prevent any

73   possible miscommunication and misunderstanding as the evaluation continues.

74   This is critical as the regulatory authority will likely be responsible for commenting

75   upon or approving the land use plan being developed. The regulatory authority

76   may have an institutional memory regarding the site that may prove valuable.

77   Understanding the rules is also critical for knowing what technologies or best

78   management practices (BMPs) are allowable for implementation. Some of these

79   may be new to the regulatory authority and to the client, so it is up to the client

80   and associated evaluator to be well-versed in appropriate BMPs (e.g. advanced

81   onsite wastewater treatment systems, rain gardens, green roofs, storm water

82   practices) and be able to explain the benefits and disadvantages to appropriate

83   personnel.


85   Collection of existing site information

86          In addition to understanding the client’s priorities and expectations, as well

87   as the applicable rules, leads to the next step, which is to gather site information

88   prior to a site visit. There are many types of materials available from a variety of

89   different sources. Start by collecting any existing, published information that may

90   help the understanding the types of soils, their properties and distribution on the

91   landscape. These may include county soil survey information, which may be

 92   obtained in one of two ways. One source would be the county United States

 93   Department of Agriculture Natural Resources Conservation (USDA NRCS) office.

 94   This information is also online at the USDA NRCS Web Soil Survey website

 95   ( (see Malo, 2008 this book).

 96          Other preliminary information sources may include the following:

 97      United States Geological Survey (USGS) topographic maps

 98      Bedrock and surficial geology maps that could be obtained from the state

 99       geological survey

100      Federal Emergency Management Agency (FEMA) maps (including flood zone

101       maps)

102      Plat maps (also called rural directories) may be obtained from the town, city,

103       or county

104      Any previous survey information, site applications, etc. for that land parcel. If

105       these have been filed with a public entity they are public record. Check the

106       local county courthouse for this type of record. Also, ask the client about any

107       records acquired during the purchase of the land parcel.

108       Many of these resources are available in both hard copy and in electronic

109   forms. Some states such as Missouri and Kansas have geospatial resources

110   available on the web ( or including

111   digital soil surveys, soil characteristic data, aerial photographs, topographic

112   maps, digital elevation models, etc., available. Additional information may be

113   obtained from the tax records or deeds as needed. Most of the maps are good

114   for planning, initial decision making, and helping understand what to expect prior

115   to a site visit. None of these materials are detailed enough to make specific,

116   intensive recommendations. A field investigation is necessary for a proper site

117   evaluation and there is NO substitute for field investigation. The evaluator should

118   assemble the specific materials (paperwork, tools and equipment – see Tables 1

119   and 2 for recommendations) that will be needed for the field. The selection of

120   tools and equipment may vary depending on intended land use and scale of the

121   project. One additional action during this phase may be the need to contact a

122   utility locator service if any excavation may occur. The number for such service

123   is often found in the phone book.


125   Re-evaluation of client goals

126          Based upon the preliminary information gathered, this is the time to

127   assess or reassess whether or not the client’s goals are reasonable for that

128   particular parcel of land. It is important to do this prior to field evaluation. If the

129   goals and values are unreasonable for the site, no matter how effective and

130   precise a job is done in the field evaluation, these goals may not be attainable, or

131   may be too expensive to achieve. This results in an unhappy client and

132   frustrated consultant which could be detrimental to a consulting business in the

133   long term. The site visit will follow after this assessment.

134                                          Site work

135   Site reconnaissance

136      Once at the site, it is important to make a circuit around all of the property

137   lines as well as a general walk across and around the site. The extent of this

138   cursory walk-around will depend on the intensity of the proposed land use. If the

139   client intends to convert a forested site into a subdivision and retain some of the

140   trees, a detailed walk over the site will be required. If, on the other hand, the

141   client intends to remove all of the trees from the site, the walk over may be less

142   detailed. During the walk over it might be very useful to have a global positioning

143   system (GPS) unit to mark features of particular interest or concern to the

144   intended land use. Furthermore, the type of inherent features to assess will differ

145   from site to site. In all cases, look for signs of buried utilities and easements, and

146   confirm that buried utilities that were found during your preliminary investigation

147   or by utility-locating services are either identified or absent. On the site plan note

148   the following observations:


150      Aesthetic features such as trees or views that the client might want to
151       preserve
152      Buildings (on property and adjacent properties)
153        Note that utilities between buildings may not be located by a utility locator
154          service
155      Chemical storage areas and old fuel barrels
156      Driveways
157      Dry ponds or similar depressional areas
158      Easements
159        Overhead power
160        Gas
161        Utilities
162        Etc.,
163      Existing sewer lines (on property and adjacent properties)
164      Existing wastewater systems (on property and adjacent properties)
165      Existing water lines (on property and adjacent properties)
166      Highly compacted/trafficked areas, such as livestock pens or parking areas
167      Percolation holes or other previous testing locations
168      Photo points (if photos are taken)
169      Proposed residence(s)
170      Property lines

171      Property corners
172      Roads
173      Road cuts
174      Borrow pits
175      Rock outcroppings
176      Soil disturbances which may indicate previous burial or excavation
177      Survey monuments
178      Test holes
179      Trash dumps
180      Vegetation (both native and planted)
181      Wells (on property and adjacent properties)
182      Water-features
183        Dry washes or ephemeral streams
184        Flood-prone areas
185        Live streams
186        Ponds or lakes
187        Swimming pools
188      All of the above features on adjacent property which may influence water
189       movement, hydrology on the site etc. should be considered

191   Topography

192       During the initial walk over it is also important to record notes on the site

193   topography. The topography of the site affects the distribution and type of soils

194   as well as hydrology. For example, a sloping site may have more topsoil near

195   the summit and toe slope than along the back slope where soil may have been

196   eroded by wind and precipitation. Soils at the bottom of slopes (toe slopes) tend

197   to be wetter than soils on the summit because saturation usually occurs at the

198   bottom where water collects. On a sloped area, soils parallel to the contour will

199   tend to be more similar than soils perpendicular to the contour. Topography also

200   affects water movement in a convergent or divergent manner so determination of

201   slope type and shape is important (Figure 1). As previously mentioned, 7.5’

202   topographic maps are available from the USGS, but are likely not detailed

203   enough for all intended site uses, in which it might be necessary to conduct or

204   commission a more detailed topographic survey.


206   Locating and determining the number of sites for detailed soil profile evaluations

207          The selection of soil evaluation site locations is based in part on the

208   understanding of the site. The soil pits need to be located in areas that represent

209   the range of characteristics of the site and representative of the soils conditions

210   used to select the BMPs selected for site development. A more comprehensive

211   soil morphological description can be obtained with soil pits. The use of

212   auger/probe borings, both before and after excavation, can assist in identifying

213   and documenting critical soil variability as well as identifying locations for

214   additional soil pits.

215          The level of detail needed for a soil description will vary somewhat based

216   upon the intended land use. If the required level of detail is high, the best way to

217   describe a soil is with a pit excavation. If pits are not available auger borings

218   may be used. For example, a site evaluation for onsite wastewater systems will

219   need to evaluate and predict water flow through the soil in the area of effluent

220   treatment and dispersal. This is accomplished by a thorough soil morphologic

221   description (see Lindbo et al., 2008 this book). The soil profile should be

222   evaluated 1- 5 feet below the expected trench bottom in order to identify any

223   restrictive layers or evidence of water table which would influence dispersal and

224   treatment. In some cases use of extensive auger boring or probes will assist in

225   understanding the soil variability. More complex landscapes will require an

226   increasing number of profile descriptions. It is generally recognized, for

227   example, that the minimum number of profile descriptions for a house lot with an

228   onsite wastewater system is 2, one in the primary field and one in the reserve.

229   However the number performed should always be enough to adequately

230   describe and evaluate the site and associated variability. In this example, as a

231   result of these evaluations a long term acceptance rate will be assigned and later

232   used by a designer to determine the appropriate size and configuration of the

233   onsite wastewater treatment system.

234          Obviously the above example requires a very detailed site evaluation.

235   This level of detail is often determined by the needs of the client. If the client

236   needs the information to design and layout a new housing subdivision, the level

237   of detail is great. If, on the other hand, the need is for a feasibility study, the soil

238   morphologic evaluation could be accomplished by multiple auger/probe boring

239   focusing on one or two aspects of the soil morphology (such as depth to the

240   water table or bedrock), or through high intensity soil mapping.


242   Additional site or soil testing

243          The detail provided by the soil evaluation may not be sufficient for the

244   selection or development of BMPs for a site. In these cases additional site

245   testing is needed. For example, if large volumes of additional water are to be

246   added to the site as with a waste water spray irrigation system, detailed

247   hydrologic information would be required, such as an assessment of the

248   infiltration rate of the soil. Likewise if a site is to be used for wetland mitigation,

249   monitoring wells may be needed to assess the pre- and post-construction water

250   table level. The selection of the location of these tests will be based on the site

251   evaluation. A description of the tests can be found in other chapters in this book.

252   Another series of site evaluations that may be needed could include groundwater

253   monitoring. Again, site evaluation will assist in the location of the wells. Details

254   on well construction can be found in other chapters in this book (Mbila et al.,

255   2008).

256            During the site evaluation, it is important to be mindful of the final step of

257   the site evaluation process, which is the communication of the results to the

258   client. Some of the site conditions may warrant further investigation through

259   specific field or laboratory testing, which will likely cost the client additional

260   money. Therefore, it may be necessary to supply a preliminary site evaluation to

261   the client then secure permission for additional testing and expenses from the

262   client. However, it is easier and more cost and time effective to do the tests

263   during the field visit rather than have to go back multiple times.


265                                           Reporting

266            After completing the field evaluation, the final step in the site evaluation

267   process should begin immediately, as details can be more easily forgotten with

268   time. It is critical to thoroughly communicate information gathered from the site

269   so that proper BMPs can be selected for the intended land use. It is also

270   important to understand what type of documentation is expected from the client,

271   such as a risk assessment, final report, or oral presentation.


273   Risk assessment

274          Risk assessment can be done at this stage to evaluate the potential

275   environmental sensitivity to the proposed land use. The parameters governing a

276   risk assessment will likely be governed by the rules and regulations of the locale

277   (local, state, and federal rules may apply) so knowledge of the rules is critical.

278   There are some fundamental guidelines to consider, such as the proximity to

279   various water bodies or receiving environments. When such environments are of

280   particular public interest (i.e. well fields, shellfish beds, recreational areas, etc.)

281   additional site evaluation may be required as well as a greater level of detail and

282   documentation related to the area of concern. In the end, more extensive BMPs

283   may be needed in order to adequately protect the public interest.


285   Final written report

286          The final step should be the preparation of a final written report. Provide

287   the client with a site description and recommendations for BMPs to accomplish

288   his/her goals for the future use of the parcel. The information should include all

289   back ground information and data gathered about the facility, any maps and data

290   generated, the site evaluation, any soil descriptions, highlights of site and design

291   considerations, and any special concerns or considerations. Detailed analysis

292   including data collected, lab reports, etc., can be placed in an appendix as

293   opposed to the main body of the report. Specific site and soil data, plus criteria

294   used for design must be provided to support the decisions and enable the

295   selection of the most feasible BMP options for the site. There should also be a

296   statement in the final report detailing how the report should be used and

297   transferred to other individuals. It is important that the client understands that the

298   report is a package and that parts or it should not be taken out of context.

299   Oral report

300          An oral presentation may need to be presented to one or more of the

301   following people or firms: the owner or developer, associated clients, designer,

302   engineer, regulator, elected officials, land use advisory boards and landowners

303   adjacent to the site being developed. It is important to review the written report

304   with the client first, then develop the presentation in concert with the feedback

305   from the client prior to presenting the material to a larger audience such as a

306   planning board, board of directors, public hearing or other regulatory authority.

307   This assures that the consultant and client are comfortable with not only the

308   material but also with the manner in which it is presented.

309                                      CONCLUSION

310          This systematic approach for performing site evaluations will allow for the

311   practitioner to collect the pertinent information and synthesize the results for the

312   client. No two consulting projects are alike, so it is important to understand that

313   site evaluations are similar to an investigation, with a somewhat unpredictable

314   ending. An understanding of the client’s values and needs, the regulatory

315   framework, and the current technologies available is essential. The framework

316   described in this chapter is an iterative process, where new information or

317   solutions and designs should be tried until a product is found that will fit the site

318   and the customer’s objectives.


320                                    REFERENCES

321   Arnold, J. A., D. L. Osmond, M. T. Hoover, A. R. Rubin, D. E. Line, S. W. Coffey,

322   and J. Spooner. 1996. Onsite Wastewater Management-Guidance Manual.

323   North Carolina Cooperative Extension Service and North Carolina Department of

324   Environment, Health and Natural Resources. Raleigh, NC.


326   Lindbo, D.L. and N. E. Deal (eds.) 2005. Model Decentralized Wastewater

327   Practitioner Curriculum. National Decentralized Water Resources Capacity

328   Development Project. North Carolina State University, Raleigh, NC.


330   Lindbo, D.L., M. Stolt, R. Miles, D. Mokma, S. Greene, and M. Hoover. 2005.

331   Soil Module Text. in (D.L. Lindbo and N. E. Deal eds.) Model Decentralized

332   Wastewater Practitioner Curriculum. National Decentralized Water Resources

333   Capacity Development Project. North Carolina State University, Raleigh, NC.


335   Lindbo, D. L., D. Presley, R. Miles, and N. Ransom. (2008 this publication). Soil

336   Profile Description. In S. D. Logsdon (ed.) SSSA Special Publication.


338   Mbila, M., D. Clendenon, and T. Tsegaye. (2008 this publication). Monitoring

339   wells and piezometers. In S. D. Logsdon (ed.) SSSA Special Publication.


341   Malo, D. (2008 this publication). Electronic soil survey data bases. In S. D.

342   Logsdon (ed.) SSSA Special Publication.


344   Schoeneberger, P.J., D.A. Wysocki, E.C. Benham, and W.D. Broderson.

345   (editors) 2002. Field book for describing and sampling soils, version 2.0. Natural

346   Resources Conservation Service, USDA, National Soil Survey Center, Lincoln,

347   NE. (


349   Soil Survey Staff. 1999. Soil Taxonomy. 2nd ed. U.S. Govt. Printing Office,

350   Washington, D.C. (


352   Trotta, P., J. Ramsey, and D. L. Lindbo. 2005. Site Evaluation. in (M. A. Gross,

353   ed.) Model Decentralized Wastewater University Curriculum. National

354   Decentralized Water Resources Capacity Development Project. University of

355   Arkansas, Fayetteville, AR.



358   Table 1: List of typical site evaluation equipment:

359      Auger or soil probe
360      Calculator
361      Clipboard with water proof paper
362      Notebook or field book
363      Required forms for city, county, state, or federal government
364      Compass
365      Level, theodilite
366      Global positioning system (GPS) unit
367      Munsell soil color book
368      Field Book for Describing soils
369      Flagging
370      Stakes
371      Measuring wheel
372      300’ tape measure
373      String lines
374      Soil knife
375      Probe
376      Auger
377      Post-hole digger
378      Tape measures
379      Shovel and/or tile spade
380      Digital Camera
381      A device to determine grade, such as a clinometer or Abney level
382      County Soil Survey
383      Topographic maps

386   Figure 1: Key slope names and flow patterns. (Soil Survey Staff, 1999;
387   Schoeneberger et al., 2002)






395   Table 2: Description of selected equipment (after Trotta et al., 2005).


397   Clipboard-

398   Having a clipboard in the field serves two purposes, first it provides a surface to

399   write on as you move around the site, and secondly, while in the field you must

400   be prepared for inclement weather conditions such as wind and rain. A

401   weatherproof clipboard can protect your documents from being blown away or

402   getting wet and illegible. Use of Rite-in-the-Rain® paperwork may be necessary.

403   It is also highly recommended that many field notes be taken therefore a notepad

404   should be available at all times to provide a means to archive notes and

405   comments. Once back in the office the notes should be transcribed into a

406   computer.



409   Compass-

410   A compass can be used to orient yourself once you get to a specific lot. This

411   device can be invaluable on cloudy days, in dense vegetation areas and

412   dissected landscapes. This is especially true in areas where GPS signals are not

413   available.


415   Flagging and Stakes-

416   Flagging and or stakes are used to for marking areas such as property corners,

417   wells, section corners or other items of interest. They assist by allowing the

418   location to be seen from a distance. If an above grade object (such as a tree) is

419   not available near the area you wish to mark, a stake can be driven into the

420   ground and flagging can be tied around it. The stake can also be labeled to

421   provide information to other contractors, or it may serve as a temporary bench

422   mark.


424   Measuring Wheel and Tape Measure-

425   Measuring distances to setbacks is one of the most important tasks in the site

426   investigation. A measuring wheel is an easy method of determining lengths. A

427   tape measure can be used to easily verify short distances or to measure the size

428   of a variety of items one may find in the field such as trees, or buildings.


430   String lines-

431   String lines can be tied between property corners to help keep you properly

432   oriented or to verify the investigation is meeting the required setbacks.


434   Shovel, probe, post-hole digger, tile spade, auger etc.-

435   Although soil morphologic descriptions are preferred via a pit, any of these listed

436   items can assist in provided further observations to depict soil variability.


438   Camera-

439   A camera is an essential item to document information to others who have not

440   seen the site or to remind you of the site such as configuration and the location of

441   items. Digital cameras (as opposed to film cameras) work well because the files

442   can be stored on a computer, easily reprinted and transferred to all interested

443   parties. Use of photographs during development is critical relative to many legal

444   and liability issues.


446   Devices to Determine Grade-

447   A wide variety of tools are used to determine the grade of a site. The consultant

448   should use equipment that he/she feels comfortable using and that provides the

449   desired degree of accuracy for the job and site.


451          Hand Level-

452   A hand level is a simple device that looks like a telescope. Just one person can

453   use the hand level by sighting in on various vertical objects on the site; however,

454   in other applications a second person may be needed to assist.


456          Clinometer-

457   A clinometer is a hand held device used to measure angles of elevation or

458   inclination.


460          Abney Level-

461   An Abney level is very similar to a clinometer in that it is used to measure the

462   value of a slope by means of arc measure and grade percentage.


464          Rotating Laser Level-

465   A rotating laser level sends out a laser beam which depending on the model can

466   be read directly on a surveyor’s rod or by a receiver attached to a surveyor’s rod.

467   The laser quits rotating automatically if the instrument becomes un-level. This

468   item can easily by used by a one person and is very accurate. Besides the laser

469   level a tripod, surveyor’s rod and possibly a receiver are needed.

470          Other-

471   There are many other items that may be used such as Theodolites, Transits and

472   Total Stations that can be used to accurately assess the grade of a lot

473   If site conditions are complicated or if legal boundaries need to be located it may

474   require the services of trained and licensed land surveyor.



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