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Site Assessment Mapping
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Rapid
Site Assessment |
This
method can be used as a general overview of site-level constraints.
There are two levels of site review
possible with this method; the first uses internet-based mapping
resources, while the second requires the use of GIS software.
The first level is ideal for a quick overview of the site's
potential constraints. The second level provides more detailed
analysis. |
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GIS
and Conservation Development |
Information on using GIS in conservation development is currently
being developed in cooperation between RI NEMO and RIDEM. |
Rapid
Site Assessment
What Is It?
Rapid Site Assessment (RSA) is a method that provides a preliminary
review of a parcel of land, using readily available computer-generated
maps and other data. The goal of RSA is to offer tools that incorporate
basic information about site features and constraints to anyone
making land use decisions, with the intention that the information
can be used in the development review process as early as possible,
specifically during the pre-application stage.
Land
developers, planners, designers and local board members will
find this approach simple and useful. It is especially valuable
for compact designs such as cluster zoning and conservation development.
For these alternative developments, thorough site assessment
is
needed to identify areas for concentrated development, areas
for protection of critical resources, and marginal areas to avoid
or
minimize impact.
While
Rhode Island towns typically require some sort of site assessment
before development, many times, important site information
is discovered
late or it is not presented in a consistent format, making
it difficult to review. By gathering as much information as possible
early in
the development process, the Rapid Site Assessment technique
enables reviewers to focus on land capabilities and protection
goals before
considering lot configuration, road layout, and drainage.
The
Importance of RSA
The site review process undertaken in many Rhode Island towns
has limitations. First, the quality of site assessment information
varies widely depending on the applicant. Not all applicants have
the same resources, creating disparity in how different projects
are reviewed. Incomplete applications are a consistent problem;
reviewers frequently do not receive information soon enough to
assess the site thoroughly, early in the process, when changes
are less expensive to make. Even when site information is provided
in a timely manner, it is not always put to best use in analyzing
land suitability and design because of map incompatibility or lack
of structured early review procedure. There is also no consistency
among town requirements, making it more difficult for developers
and engineers to know what to expect. In addition to these administrative
issues, marginal sites that were once considered unprofitable due
to site constraints are now being developed as growth pressures
drive up land costs. More intensive review procedures are necessary
for these more sensitive lands.
RSA Is Compatible With
Other Methods
The ideas and procedures outlined in this document are not new.
They are based on long-established principles in planning, landscape
architecture, and soil science. The Rapid Site Assessment technique
simply takes advantage of information sources that have become
much more widely available due to the evolution and availability
of Geographic Information Systems (GIS) technology and data. This
procedure is fully compatible with the four-step conservation design
technique advocated by leading landscape architects and planners
and widely used as standard practice in creative land development
design. By suggesting two or more alternative development sketches
at the early pre-application stage, the process encourages creative
and environmentally-sensitive design while highlighting the need
for flexibility and discretion in regulations.
How Does RSA Work?
The analysis is divided into two levels. The Level One Analysis
uses a simple photocopy of the plat(s), a USGS Topographic map,
and a series of resource maps readily available through the Internet.
Individuals with limited information resources and no GIS experience
could complete a Level One Analysis entirely on their own. The
Level Two Analysis requires more detailed resource data from either
Geographic Information Systems (GIS) or hardcopy sources, along
with a basic site survey and proposed development concept sketches.
This more advanced analysis requires a moderate to high skill level
and is more appropriate for professional planners or engineering
firms. However, with the advent of Internet Map Server (IMS) technology,
detailed data layers and customizable maps are easily obtained
and can be used to complete a Level Two Analysis.
Benefits
of Rapid Site Assessment
- Allows the evaluation of
the relationship of the parcel to the surrounding site from a town
or watershed perspective.
- Aids in identifying townwide
protection priorities using planning-level information and town
plan goals.
- Helps avoid premature
decisions that lock the developer and Planning Board into one design
before all options have been
evaluated. Early
assessment and consensus on reasonable design options helps
avoid backtracking (and associated engineering expense) to evaluate
new options or redesign at later stages.
- Identifies general site
suitability for development. Identifies areas with severe development
constraints where construction
costs are higher as well as sensitive areas where disturbance
should
be minimized to reduce environmental impact.
- Identifies most suitable
areas for Individual Sewage Disposal Systems (ISDS) and stormwater
controls and helps focus field
investigations.
- Provides a
clear understanding of constraints and opportunities in user-friendly,
visual format as basis for reaching
agreement on preferred options.
- Documents
factors considered in selecting design; enables town to show
basis for board decisions
in a user-friendly visual format.
- Takes advantage
of readily available high resolution, extensive RIGIS database.
Data are
readily available at both town and watershed
scale, fostering watershed- based planning.
- Provides
recent land use data (1995) that is more current than most
town maps (1988).
- Provides access
to data such as DEM Natural Heritage Areas that may not be available
at the town level.
- Provides enhanced
data and standardized formatting such as soil hydrologic groups.
Limitations of Rapid Site Assessment
- Not all consulting professionals currently use GIS. However, the
same process can be performed with large format hard-copy
maps such as those being produced through the DEM Greenspace Project
or the RI HEALTH Source Water Assessment Program.
- RIGIS
information is useful for concept-level planning only. Onsite
surveys are needed at the later pre-application
phase, to
include:
1. high-intensity soil survey to provide accurate boundaries and
classifications
2. wetland edge delineation and vernal pool mapping
3. topography (2 ft. contours)
4. vegetation mapping
5. other natural, historic, archeological, and scenic resources
as required by the town
Level
One Analysis
This first level of analysis can be performed by anyone with access
to the Internet and a color printer. It can also be done using
conventional hard-copy maps, but this can be more difficult because
these maps come from many diverse sources at different scales.
Townwide maps were used for the case study discussed below and
shown above because the development site was well within town borders.
Depending on site size and location, you may want to use either
town or watershed map format (or perhaps both).
These
maps are useful for basic early review of any project. They enable
the developer and local decision makers to:
- Visualize
how the project site fits in the surrounding environmental and
social context of the community, a type of
analysis that is
otherwise often limited to a fuzzy location map;
- Review
features beyond the project boundary that might otherwise be
overlooked, especially for projects located near
town borders;
- Better
address town goals for the general project area before focusing
on specific features of the site.
Although resolution of the maps used here is limited, the
fact that they are free and readily available makes them
a valuable
resource as long as their limitations are understood.
How To Conduct
a Level One Analysis
Step 1. Locate the approximate boundaries of the proposed site
on plat or through materials provided by the applicant. Note
landmarks such as road intersections and streams that will help
you locate the site on the other maps.
Step
2. Visit
RI Critical Resource Atlas Web Site (http://www.edc.uri.edu/riatlas/) and
download maps for printing. Maps on the digital atlas are obtained
by selecting the town or watershed you want, and either
clicking
the map of interest (Town Atlas or Watershed Atlas) and then
choosing the town from the associated list, or choosing the name
of the town
or watershed on the drop-down menu. Once you choose the town
or watershed you want, it will move to another page where you
need
to scroll down to see the maps. Choose the map and format (8.5" x
11" or 20" x 20") you want, and after the
map appears, you can either print it or save it to your hard
drive
for future use. To save it to the hard drive, right-click and
choose "save
image as".
Step
3. Once you have printed the maps, locate the site and pencil-in
the approximate site boundaries on each map. Each of the map types
are listed below with findings for our site example.
In addition
to these maps, use a USGS Topographic (1: 24.000) map to become
familiar with the terrain. Topographic images are
available
from USGS or the RIGIS web-site (http://www.edc.uri.edu/rigis-spf/rigis.html).
In the RIGIS website, click on the map for USGS Quad Data or
scroll down to the town of interest under the map for Quad
Data. Pick
the town you are interested in and then scroll down the page
to view available maps. Under “Raster Images” there
are usually two choices, both for USGS 7.5 minute Topo Quad.
Choose
the file associated with “USGS 7.5 minute Topo Quad” by
clicking on the zipped file (link to the far right in the table)
and then save to your computer. The file is in tiff format
and can be viewed in most photoediting programs as well as
by importing
into wordprocessing software. The file will have to be unzipped
before viewing and printing.
About
the RI Atlas Website
The RI Atlas provides pre-made GIS-bases maps for both towns
and watersheds. These come in 8.5" x 11" and 20" x 20" formats
that can be viewed online, printed, and downloaded. Once maps are
downloaded, they can be brought into documents for reports or presentations.
One technique to provide larger visuals with small-format color
printers is to use the 20" x 20" format and crop it (in
the word processing or presentation program) so important sections
can be printed larger for visibility. If you choose this technique,
be sure to print out the entire map in the letter-size format so
you can analyze context.
There are
several advantages to using the RI Atlas. First, it is easily
accessible and covers all Rhode Island Towns and watersheds.
Secondly, when a project is close to or straddles a town boundary,
you can download consistent maps for both sides of the boundary.
The atlas also has good soil hydrology information, that is not
directly available on RIGIS, as well as information on rare species
habitat. It is important to note that the rare species habitat
information has not been updated in several years, so it is still
important to contact RI Natural Heritage Program for more up
to date information as the development project moves forward.
A
Note About Scale in the Level One Analysis
Level One Analysis uses data at its intended scale
or smaller, avoiding the scale-error problem, but providing only
a very crude overview. This means that if you use the data source
provided for the Level One Analysis, and mark your development
parcel on this map, that there are no problems with zooming into
a map too closely so that it appears the data is more accurate
then it really is. When completing the Level Two Analysis (discussed
below), using interactive maps, often you are zooming into
the data at a finer
scale than the data were intended for. This provides a more detailed
picture than Level One Analysis, but remember - the data are
not necessarily accurate at this scale. All site characteristics
should be confirmed through groundtruthing. More information
on scale can be found on the Mapping Basics page of this website.
Level One
Case Study
Using a 300-acre example site in Hopkinton RI, this case
study was completed using the Level One Rapid Site Assessment Method.
Each
map is shown with basic information on the map. Click on the thumbnail
of the map to see it in a larger view.
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Overview- This map provides a clean base to locate the site.
It also shows proximity to facilities such as schools, libraries,
and other municipal services. In our Dye Hill road example,
we found that the site abuts a large protected area. One priority
may be to preserve open space on the site to foster greenway
linkages and preserve wildlife habitat. |
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Forests
and Wetlands- This map begins to give an idea of ground cover
and wetlands issues on a site, and how these resources relate
to surrounding context. It is important to note that at this
scale only large wetlands, ponds, and streams are shown.
Although it is based on wetlands maps where the minimum wetland
size is quarter-acre, these smaller wetlands will not appear
because of the small printout size. Consult USGS maps and
large format hard copy wetland mapping (level 2) if possible.
In our Dye Hill Road example, we see that the site is mostly
forested, with some fields or brush. What are the development
opportunities and constraints related to these types of ground
cover? |
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Land
Use- This map lets us see what types of development and land
cover surround the site. Residential development is broken
up into different densities, giving an idea of the character
of the surrounding area. In our example, we see that our
site is mostly deciduous forest with a bit of mixed forest
to the northeast. There is some agriculture (not necessarily
active) towards the front of the site. That section of Dye
Hill Road has fields on both sides. How will development
affect the character of this stretch of roadway? |
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Groundwater
Resources- The mapped groundwater aquifers are areas of significant
volume of groundwater, sometimes referred to as the groundwater
reservoir. Recharge areas show the drainage region that provides
rain infiltration into the aquifer. Wellhead protection areas
provide direct groundwater recharge for public wells. The
wellhead protection area for larger public wells (yielding
greater than 10 gpm) drilled in outwash (sand and gravel)
deposits are delineated using a groundwater flow model which
tends to produce an irregularly shaped wellhead delineation.
The wellhead protection areas for smaller wells and those
drilled in bedrock are delineated using a standard formula
which results in a circle with a radius of 1,750 feet. Because
all land use activities in these recharge areas affects the
quality of the underlying groundwater, development occurring
in any of these resource areas requires special management.
Our site off Dye Hill Road lies partially in a wellhead protection
area. It does not lie over any aquifer or recharge area. |
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Biodiversity-
This map is a very convenient source for rare species habitat
locations along with the same protected open space as the
overview map. There are no designated rare species areas
within our site. There is one area just to the nortwest,
and another downstream on the Wood River. How will cumulative
development in the upper watershed affect this rare species
habitat? |
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Coastal
Wetlands- Usually, this map breaks coastal wetlands
into different categories. Although it would be very valuable
for analysis
in a coastal community, it was not useful in our example
because Hopkinton is landlocked. |
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Soil
Hydrology- Soils are mapped by hydrologic group (permeability)
and depth to water table. Areas with restrictive and high
water table soils have significant constraints and management
issues because of the likelihood of septic system failure,
seasonal flooding, and pollutant runoff to surface waters.
Excessively permeable soils increase pollution risk to groundwater,
but are also valuable for recharging groundwater. The Dye
Hill Road site is mostly in dry well-drained soils, but has
several areas of moist (seasonally wet) soils running through
its center. What is the best way to design the site with
soil conditions like these?
Note
that the color scheme for soil hydrologic group and depth
to water table has been updated, other maps of the same
data may exhibit a modified color scheme; this does not
affect the
data.
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Watershed
Sub-Basins and Surface Water- Drainage basins are
the area of land that drain into rivers, streams, ponds,
and
estuaries. This map is useful for locating a project in the
sub-basin, but does not delineate watersheds within the sub-basins.
For our Dye Road site example, we see that the site is in the
Wood River Sub-basin. From the streams and ponds on the map,
we can see that the site is directly upstream from a large
pond. The USGS Topographic map reveals that it is Locustville
Pond and our site is within the Pond's watershed. One thing
that stands out is that there is a stream shown on the USGS
Topo running right through the center of the site that does
not appear on the RI Atlas maps. This is a minor tributary
to Brushy Brook, and only major streams were mapped in the
RI Atlas. This emphasizes the usefulness of the USGS Topo map.
Since only major basins are shown in the RIATLAS, the local
subwatershed must be delineated using elevations from a USGS
topographic map, as we have done here. What management practices
can be used to protect ground and surface water quality?
Other
publications provide information on existing water quality
in the pond. In this case, we referred to the Pawcatuck
Watershed Report (Pawcatuck Watershed Partnership 1998)
and found out
that Locustville Pond is Class B (habitat, recreation,
aesthetic value- not a drinking water reservoir) but is
threatened for
aquatic habitat by noxious aquatic plant growth caused by
non-point source pollution. Monitoring data collected by
Watershed Watch citizen volunteers documents that the pond
tends to be enriched with nutrients (URI 1998). Brushy
Brook, the small stream that runs through the southern
portion of the site, is Class A (highest quality) and is
fully supporting these uses in this area.
How
much of the Locustville Pond area has been developed and
with what use?
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USGS
Topographic Image`` |
Level
Two Analysis
The
Level Two Analysis is very similar to the conservation
mapping process. The site is
evaluated with a greater level of information than what is available
under the Level One Analysis. Under this Level Two Analysis, project
specific maps are produced, generally using GIS software. These
maps should have a greater level of detail than those produced
under the Level One Analysis. Ultimately, the Level Two maps are
reviewed to determine areas that should be left in a natural state
and those areas that constitute the best development sites. This
should be an iterative process; as the process progresses with
the involvement of both the developer and municipality, updated
and more accurate information should replace initially-available
data, further refining the development plan.
In most towns, all of the site features mapped in the Level
Two Analysis are already standard requirements of a subdivision
submittal. (In fact, the applicant may find it more cost effective
to provide the general site information as GIS overlays.) The information
is available, but not always fully evaluated before proceeding
to detailed review of road layouts. More thorough attention to
site features can be useful in reaching agreement on areas to focus
development and areas to protect.
The
Need for Site-Specific Information
GIS coverages provide screening level data that is useful only in the earliest
pre-application and concept review stages. Site-specific information such as
two-foot contours and verified wetland edge are needed for accurate site assessment.
Many project consultants agree that obtaining this data sooner rather than later
is well justified given its importance in road layout, siting buildings, designing
stormwater drainage systems, and siting septic systems. In addition, up-to-date
vegetation surveys, location of stone walls, and identification of other unique
natural, cultural, historic, and archaeological resources is required in early
site design.
Two
other types of analysis not typically required but that provide
essential data in early site design are: site-specific
soil survey mapping and vernal pool mapping.
Vernal pools provide important habitat for increasingly threatened
salamanders, frogs, and other amphibians and reptiles, but they
are not protected by state regulations. These temporary pools
can easily be identified and mapped by wetland consultants hired
to verify the presence and extent of wetlands.
A
site-specific soil survey is necessary to verify that state-mapped
soils are accurate at the site level. The RI Soil Survey has
been proven to be remarkably reliable, but it is a planning tool,
not intended for site level analysis. In addition to the problem
of scale (the boundary line between two soil types on the map
can vary by 40 feet in the field), soil complexes occur that
include different soils types with dramatically different characterstics.
Because these soil types occur together in association, they
can only be mapped accurately through a site-specific survey.
Recognizing
the value of better soils information, the Rhode Island Department
of Environmental Management (RIDEM) has revised regulations for
onsite wastewater treatment to require that licensed site evaluators
with training in soil science be permitted to determine septic
system suitability. In addition, RIDEM is moving towards a more
soils-based approach to site assessment that will reduce reliance
on perc tests and increase use of soils data to estimate water
table elevations. Given the importance of soil evaluation in
septic system suitabiity determinations, it makes sense to rely
on accurate soils information to first identify potential areas
for building sites, septic systems, and stormwater drainage systems.
Site-specific soil surveys are especially important for towns
with soil-based zoning but are not routinely required.
Recommendations
for Level Two Analysis
- For
major subdivisions and other large projects the municipality
could require the developer to assemble coverages used in the
Level
2 analysis and using these, demonstrate how the proposal achieves
town goals for the area and minimizes potential impacts. At a
minimum, the town should require the applicant to completely
present the
site analysis information before any road layout. The site analysis
should identify optimum sites for development, critical areas
to be preserved, and marginal areas where disturbance will be
minimized
to avoid impact. The findings of the site analysis can then be
used to develop at least two concept sketches that can be used
to select conventional vs.alternative designs.
- Towns
should consider requiring vernal pool identification whenever
wetland edge delineation
is specified. This would include pool
mapping, and potential travel areas or hydrologic connections
to other pools. Since vernal pools are not regulated by DEM and pool
boundaries are not verified by DEM, the town may have to hire
their own wetland scientist to verify vernal pool locations.
- For
large projects or those in sensitive areas, the municipality
should require a site-specific soil survey, conducted by a qualified
professional soil scientist, certified by the American Registry
of Certified Professionals in Agronomy, Crops, and Soils
(ARCPACS).
- For
large projects, those in sensitive areas, or those where
the town requires and environmental assessment, results of
detailed
site investigations such as wetland and soils mapping, vegetation
types,
and other site features would be incorporated into
a much
more accurate overlay analysis.
- The
Natural Resources Conservation Service, in cooperation with
State agencies, municipalities, URI, and the Southern
New England Soil Science Society, should consider developing
consistent standards
for site-specific soil surveys for the southern New
England region. These could be adapted from standards currently
used in northern
New England. In addition, these groups should consider
standardizing data requirements for site review as guidance
for Planning Boards,
such as those used by the State of New Hampshire.
How
To Conduct a Level Two Analysis with Level Two Case Study
Field
investigation
The reviewers and applicant should conduct a field investigation
to be sure that submitted site information is correct. The reviewers
should:
1. Walk the site to identify important factors that were missed
in the initial data gathering.
2. Note large trees and other distinctive vegetation for preservation.
3. Envision road and house placement and accompanying impacts.
4. Evaluate the proposed access point and width of the entrance
(sight lines, impact on wetlands and stone walls).
5. Interview neighbors for their concerns and point of view.
This
is an excellent opportunity to reinforce information learned
from the maps, as well as to develop map reading skills in the
field and identify any areas that have changed or were not
included.
Assembling
data and maps
Most data necessary for this analysis are available on the RIGIS
website. RIGIS data will need to be downloaded and,
using a GIS software package, manipulated to produce the series
of
maps exhibited below. Information on recommended layers to
use in map
production is available in the document Site Assessment
Mapping for Development. Detailed descriptions on how to produce
the
necessary maps are not provided here.
Each
of the required maps is exhibited below along with a basic description
of the map components and key questions
to ask
regarding the map information. The maps presented are for
a site in Hopkinton,
RI.
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Topographic
Features- This image will show the general contours
of the land.
Questions
to ask:
· What is the general lay of the land?
· Which areas will be most disturbed through grading?
In
the Dye Hill Road site, there are some substantial slopes
(8-15%) and stony soils, with some rock outcrops (CeC),
increasing construction cost for roads and foundations.
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Orthophotography-
An aerial photograph at the same scale as map data provides
excellent site orientation. This one is from ortho.edc.uri.edu.
Questions
to ask:
· What is the general lay of the land?
· How is the land currently being used?
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Soils
Constraints- The Soil Survey of Rhode Island is
a rich source of development constraint information. General
soils data
allows determinations of specific areas of the site that
may be unsuitable for development. The soil constraints
map can be produced using the general soils layer color
scheme
located under the References section of this site.
Additionally, erodible soils can be highlighted if they
are a problem for your site.
Questions
to ask:
· Where are the hydric (wetland) soils (Hydro-Group D)?
· Where are the high water tables (Hydro-Group C) soils?
· Are there restrictive layers present (Hydro-Group C)?
· Where are the best soils for ISDS placement (Hydro-Group B)?
· Where are excessively permeable (Hydro-Group A) soils?
· Are there any very stony soils or rock outcrops?
· How do the various water table depths affect suitability for
ISDS and storm drainage structures (see reference table
below)?
Facility
Minimum Separation Distance from Water Table
Septic System Drainfield: 24"
Drainage Swale: 24"
Storm Water Pond: 12"
Infiltration Basin: 36"
Source: RIDEM Regulations
The
Dyer Hill Site is primarily well-drained hydro-group B
soils (Charlton-Canton CdA, ChB, ChC, ChD), with some restrictive
high water table C soils (Ridgebury Rf) along the tributary
of Brushy Brook. Some high water table B soils (Sutton
SuB) connect fingers of C soil, creating a substantial
extended drainage network. There are some excessively permeable
A soils (Hinkley HkC) near the site entrance along Dye
Hill Road that may pose a threat to groundwater if improperly
developed. One constraint that particularly stands out
is that almost the entire site has highly erodible soils
because of the steep slopes and soil composition. Erosion
and sedimentation controls should be carefully applied
and monitored throughout construction. Site designs that
limit disturbance and minimize impervious cover will be
most effective in avoiding erosion impact. See the Understanding
Soils section of this website for more detail on analysis
methods and management practices.
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Hydrologic
Features- This map should indicate drinking water
reservoir watershed, wellhead protection areas, ponds, streams
and
any other water resources.
Questions
to ask:
· Is the site in a drinking water reservoir watershed, groundwater
protection overlay zone, aquifer recharge areas/ reservoir,
or wellhead protection area?
· Where are surface water bodies located (streams, rivers, ponds,
lakes)? How do they function in natural site drainage?
· What watershed is the site in (sub-basin level)?
· Are there any rare wetland types on the site (i.e. bogs, fens)?
· Are there vernal pools on the site (must be varified in the
field)?
· Is the site in a floodplain?
As
noted above, a tributary to Brushy Brook, which feeds Locustville
Pond, runs through the site. There is a small pond on the
easternmost
tributary. Wetlands include deciduous forested, shrub-scrub,
a marsh or wet meadow near the site entrance, and a shrub-scrub
bog to the west. Bogs in particular are very sensitive
to disturbance and this should be considered during construction
grading and ISDS siting. Note that there are wetlands on
the site that do not show up in the RI Atlas maps used
for the Level one analysis. The RI Atlas only covers large
wetlands, but the RIGIS wetlands data (available on the
web) includes wetlands ¼-acre and up, classified
by type.
Some
of the southern end of the site lies within a Community
Wellhead Protection Area (serving year-round residents
with at least 15 connections or 25 residents). This area
coincides with a band of excessively permeable outwash
soils. A
small amount of the site near the entrance along Brushy
Brook
is in Flood Zone A.
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Open
Space- Open space protected by various agencies such as
the municipality, Audubon Society and the State are indicated.
Questions to ask:
· What types of open space are present on the site (i.e. open
meadow, deciduous forest, and coniferous forest)?
· Is the open space contiguous or fragmented? Is it possible
to connect the open space with the larger regional scale?
· Greenway Linkages: Will the designated open space be connected
to a larger greenway network? Will wildlife migration
paths and access to water be contiguous?
Our site has deciduous and mixed forests, brush, and
small clearings. It is contiguous with two large
sections of
Arcadia Management area, creating a forested connection
broken only
by Woody Hill Road and associated low density residential
development. The State Greenway Corridor runs southwest
of the site but
there is no direct connection (See also Level 1 Land
Use and Biodiversity).
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Scenic
Views to and from Property- Scenic views are indicated
by the State as well as determined during site visits.
Questions
to ask:
· Are there scenic views from or into the site?
· Are there historic or natural features that can be used as
focal points (i.e. rock outcrops, historic trees, stone
walls, coastal views)?
The
area all along Dye Hill Road has been designated scenic
by the RI Department of Environmental Management.
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Historic
and Cultural Resources- The location of stone
walls, historic cemeteries, Native American Burial Grounds,
historic
homes,
and farms should be indicated. This information can be
partially found on the RIGIS data, but should also be determined
during
a site visit.
Questions
to ask:
· What historic or cultural resources should be preserved?
· What historic or cultural resources must be preserved based
on State laws.
According
to RIGIS data, there are no archeological or historic resources
on the site, but these data are limited.
There are
several candidate and registered historic districts to
the south. A detailed survey
is needed
to identify stone walls and other historic and cultural
resources.
Rare
Species and Other Wildlife Habitat- This information
could come from the Town's Conservation Commission, DEM
Natural
Heritage Program, or The Nature Conservancy. This information
is generally mapped with historic and cultural resources
information.
Questions
to ask:
· Are any rare species or protected wildlife habitat on the
site?
Two
DEM Natural Heritage Program rare species areas lie north
of the site, one along Woody Hill Road and the other
within
Arcadia Management Area. There is another rare species
area south of the site along the Wood River. Only DEM
and RIGIS
coverages were used in this example, but another important
resource is GIS data from the EPA Rhode Island Resource
Protection Project.
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Synthesizing the Data
Some general questions that emerge from a Level Two Analysis are:
- How
does this site fit into the larger landscape?
- How
will this subdivision impact neighboring
sites?
- Does
it conform to the goals of the Comprehensive Plan?
After
considering all the issues, the board or committee
should
work with the developer and consultant to:
- Delineate
priority areas for preservation and desirable areas for development.
- Consider
potential impact to resources on the site and in the surrounding
area.
- Determine
the point of entrance and preliminary road layout.
- Determine
areas where shorter road layout, reduced roadway width, and
alternative paving materials may be
used to reduce
pavement.
- Integrate
stormwater controls into design, preserving well-drained areas
for infiltration; determine
where non-structural
stormwater measures can be used for roadways and on individual lots.
- Determine
the degree of grading on the site (minimize where appropriate).
- Determine
the type of ISDS (conventional or innovative) appropriate
for the project. For example, some design tradeoffs
may involve placing part of a house lot in seasonally wet soils.
Innovative drainfield design or placement can help avoid
an unsightly mound system.
- Determine
most effective erosion control measures before, during and after
construction to minimize impact.
The purpose of this step is to identify the most appropriate
areas for development and preservation, determine mitigation
for marginal
areas that will likely be developed, and assess whether
creative/flexible development techniques will further
Town goals expressed
in the Comprehensive Plan. If reviewers determine that
creative/flexible development techniques could provide
a significant benefit
and
are provided for somehow in the zoning ordinance, the
site analysis process described above lends itself directly
to the
four-step
Conservation Subdivision design process advocated by
planners
such as Randall Arendt, Dodson Associates, and others
(Arendt, et. al.
1994).
For
the Dye Hill Road example, Dodson Associates designed a conservation
subdivision concept sketch based on the Level Two Analysis
described above, seen here with topo or soils.
GIS
and Conservation Development
Information
on using GIS in conservation development is currently being
developed in cooperation between RI NEMO and RIDEM. It is anticipated
that GIS data layers with appropriate legend information will
be available to streamline the procedure to prepare maps under
conservation development in the near future. Additionally,
an ArcExplorer project with the same data will be made available
for use by those without ArcView licenses.
This
data is anticipated to be available early in 2007 and will
be made available on this site.
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