ch 6 soils and land use

8/3/2019 Ch 6 Soils and Land Use

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Soils and Land Use

Land Use Properties of Soils and Soil Quality

Soil Surveys and Interpretive Soils Mapping

Land Application of Wastes Soil Erosion, Assessment, and Mitigation

Urban Soils

Agricultural Lands and Land Evaluation andSite Assessment (LESA)

Urban Agriculture and Food Systems Planning


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Wetland Soils

Hydric conditions

Land Use

Properties of

Soils


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Soil Stability:

Unified Soil Classification System


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Soil Drainability


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Soil Erodibility:

4 types

of watererosion


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Soil Productivity and Resource Value:

USDA Agricultural Land Capability Classification


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USDA Textural

Classification of

Soils


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The Modern Soil Survey


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Step 2: List soils and their rating or

limitation from soil survey tables


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Step 3: Make table sorting soils by category:

Limitations for Dwellings with Basements


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Dwellings with basements


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Dwellings with basements


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Web Soil Surveyhttp://websoilsurvey.nrcs.usda.gov/app/HomePage.htm
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htmhttp://websoilsurvey.nrcs.usda.gov/app/HomePage.htm


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Soil Data Mart: http://soildatamart.nrcs.usda.gov/
http://soildatamart.nrcs.usda.gov/http://soildatamart.nrcs.usda.gov/


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Soils and On-site Wastewater and

Land Application of Wastes On-site septic systems

Sanitary landfills

Sewage sludge biosolids

Animal manures and nutrient management


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On-site Wastewater Systems


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An aside: Sewers and

Septic in Blacksburg

Parts of the town unserved

700 septic systems

Future of Toms Creek basin?

New sewer interceptor

proposed in 2002, but the basinis zoned for rural residential

Concern: Build it, they will

come (dense development

follows infrastructure)

Approved by Council, thencitizens voted Council out

No sewer line!

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Existing Public Sanitary

Sewer Service Areas

November 27, 2001

Town of Blacksburg

G:\04Complan\Whole town\Utilities\Sewer.dwg

Areas with Public Sanitary

Sewer provided

Virginia Tech


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So then

what? Toms Creek area will

develop in clusters

with open space

Is conventional septic

a good idea?

No, but there are

alternatives:

Septic tank effluentpump/gravity systems

(STEP/STEG)

Proposed Houses

Open Space

Natural Hydrology

Conceptual Development of

the Tom's Creek Basin at

Full Buildout


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Village at Toms Creek STEP/STEG System


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Soil Erosion: Some success


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Revised Universal Soil Loss Equation

(RUSLE)


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Erodibility Factors in Soil Survey


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Erodibility Index and HEL

Erodibility Index (EI) = K x R x LS

T

Where:

T = Erosion Tolerance (usually 3-5 tons/acre)

(values are given in Soil Survey)

Highly Erodible Lands (HEL) have EI>8


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RUSLE2 Software:http://www.ars.usda.gov/Research/docs.htm?docid=6038

Chose a location to set climate: from the pop-down menu which

reveals states then general area with in the state. Pick the nearest

location to your site and it will set the r value.

Choose the soil type: this is done by textural class and high-medium-low organic matter and permeability, all of which can be gleaned

from the soil survey for the site.

Set slope topography: length and steepness are simply entered.

Select and modify management: this sets the c value by selecting

from an extensive pop-down menu of values specific to land use,cover, and management.

Set supporting practices: this sets the p value from pop-down

choices under contouring, strips/barriers and diversion/sediment

basin.
http://www.ars.usda.gov/Research/docs.htm?docid=6038http://www.ars.usda.gov/Research/docs.htm?docid=6038


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Erosion & Sedimentation Control Practices


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Urban Soil Problems

Soil Compaction: increased bulk density caused by anyweight on land surface, such as construction equipment,vehicles, and pedestrians. Compacted soil inhibits drainage,aeration, and root growth, and behaves like impervioussurfaces.

Impervious Surfaces like roads and parking lots interruptexchange of gases, alter drainage, and increase soiltemperature.

Moving Soils through grading and clearing eliminates topsoil,

increases erosion, and affects drainage and aeration. Soil Contamination: chemical spills, waste dumping,

excessive fertilizer/pesticide use, and runoff pollutioncontaminate soils.

Use of Fill Dirt affects drainage, aeration, and compaction.


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Erosion and Sediment Control Planning

Design Phase Evaluate the site: topography, drainage, vegetation, soils, rainfall patterns.

Divide the site into the natural drainage areas

Plan the development to fit the site.

Determine limits of clearing and grading. Divide the project into smaller phases.

Divert water from disturbed areas, minimize length and steepness of slopes, avoid

soil compaction Select temporary and permanent erosion and sediment control practices:

Soil stabilization (soil cover: vegetative and non-vegetative covers)

Sediment control (sediment filters, basins)

Runoff control (diversion, check dams)

Construction Phase

Temporary structure practices Erosion control blankets, Straw bale dike, Silt fence, Temporary swale

Operation Phase

Maintain installed E&S practices


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E&SC Example1. Grassed diversion

swale

2. Cut made for thebuilding is stabilized

3. Clearing done only

where necessary

4. Pond is constructed

on the lower terrace5. Bridge is built over

No Name Brook

6. Grassed diversion

swale above cut for the

access road

7. Access road entrance

is stabilized

8. Filter fence is

constructed along the

access road and parallel

to Pine Creek


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Agricultural Land Conversion


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Tools to Protect

The Working Landscape

Agricultural Zoning

Exclusive

Non-exclusive Cluster/Conservation Zoning

Conservation Easements/

Purchase of Development Rights

Transfer of Development Sites

Agricultural Districting

Differential Use-Value Taxation


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Land Evaluation and

Site Assessment (LESA) Land Evaluation (LE): rates soil

capability for agriculture; groups soils into

10 categories rated 0-100 points

Site Assessment (SA): rates sites non-soilfactors affecting suitability for agriculture;

sum-of-weighted-factors totals 0-200points

LESA = LE + SA = 0-300 points


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LESA WS #2: Land Evaluation Groups & Relative LE Values


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Indicator Crop Yields from Soil Survey Table

Site Assessment Factors, Scoring, Weights, Adjusted Weights


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Uses of LESA

Evaluating rezoning requests for lands zoned

for agriculture

Impact assessment

Prioritizing or qualifying sites for land

conservation programs, e.g., Agricultural

Districts, PDR, TDR, Conservation Easements


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Critique of LESA

Pros

Considers soil and non-soil factors

Flexible so communities can use own factors

Sum-of-weighted-factors judgments made bylocal committee

Cons

Relative value of soil factors (1/3) questioned Flexibility can lead to misuse

County-specific factors/weights make itdifficult to compare values between counties


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Urban Agriculture and Food

System Planning Food has become an important part of

sustainable community planning:

Access to local food, organic food, groceries

18,000 community gardens in the U.S.

6,132 farmers markets up 16% since 2009

Composting gives back to the soil

About 15% of worlds food is grown in

urban areas


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Community Food System

Troy Gardens, Madison, WI31 it 5 ff d bl h i d l t


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Community Gardens

31 acre site: 5-acre affordable housing development

300 community garden plots

5-acre community supported agriculture (CSA) farm

Prairie preserve and hiking trails

ch 6 soils and land use

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