Site Selection

Site Selection – case study of a library There are several factors that should be considered during site selection for a library. These include the • availability of land and its acquisition, • soil conditions, • accessibility, • climate, and • Legal issues such as approvals for use and construction. Each of these factors will affect a library’s real and perceived success whether success is measured in terms of the • quality of the design, • construction cost, • meeting the budget and building schedule, • or patronage

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Geography

Finding the proper site for a library is contingent upon understanding whom the library might be serving. •

A central library, used by patrons from adjacent areas as well as by those who might come a great distance, is usually sited in relation to major civic facilities.

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Branch libraries might also be placed in a satellite civic center. Often, however, the location of a branch library will be determined by its service area, the zone a majority of patrons most likely will come from. (This concept is similar to the retailers’ “catchment area.”)

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Another determining factor is the availability of land and its cost

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Generally, a central library in a large or mid-sized city should be in close proximity to other civic institutions such as a city hall, cultural centers, major open spaces (plazas and parks), and educational facilities (high schools, a college or university).

Centrality can be measured by distance, by accessibility (the hub of a regional transportation system), by relative density, by population distribution, or by proximity to other land uses such as schools.

1.2

Land Acquisition Once a general area has been agreed upon for a new library, a specific site must be secured. It is important at this point to have an understanding of the library building program. How many square feet should the structure be? Will it be constructed in phases? Will the facility be expanded over time?

1.3

Soil and Site Infrastructure Understanding soil conditions, including the relative stability of the soil and its capacity to support a structure (bearing capacity), is an essential component in site selection. While a construction system can be designed to make almost any parcel of land a buildable site, the composition of the soil and the location of bedrock (assuming there is bedrock) will influence the overall design of a structure and determine the options available for structural footings. The type of footings required has implications for building costs.

Infrastructure refers to the provision of services including but not limited to power for equipment, heating and cooling, water, data and telephone lines and the elimination of waste and storm runoff from the site. While assessing sites during the selection process one criteria should be the availability and location of infrastructure. Ideally, a potential site will have basic services provided up to the edge of the property line or along a public right-of-way. If a site is in a less developed area, services must be brought to the site from a remote location. The costs for making these connections and running services to the site must be factored into the project budget. On occasion, services and utilities already in place on a site may need to be relocated to accommodate the proposed building.

1.3

Measuring a Project’s Size 1.3.1Determining the overall size of the project

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Library space programs usually describe net program area, or net square feet (NSF = area of specific library functions such as reading rooms, stack areas, customer service and administrative offices, but do not include common building spaces like public circulation areas, restrooms, and mechanical rooms).

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The program will also define the gross program area, or gross square feet (GSF = a total measurement of everything that must be contained in a building). The gross square feet (GSF) is the only building measurement of concern during testing of the building’s fit on a site. This gross program area can then be arranged and assessed on candidate sites in a variety of building footprints.

Determining parking need •

The amount of land needed to accommodate surface parking or a parking structure can be significant. Each vehicle can require between 300-350 square feet of space, depending on the stall size, circulation pattern and type of structure.

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Most libraries provide parking directly on-site, where it becomes a key siting issue that impacts overall site access, building orientation, and the location of the front door.

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In some urban areas, a project’s required parking can be provided at an adjacent, off-site facility.

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One option is to establish shared parking where adjacent commercial structures or educational institutions will allow use of their parking facilities if the library’s peak demand time is different from their own (e.g. a library busiest at night, during a time when retail stores are closed)

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The required number of parking stalls will be determined by the applicable local parking code.

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It will also define minimum stall sizes and drive aisle widths.

Allowing for site amenities •

Open space is an important site amenity for public facilities.

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Outdoor areas for programmed activities, casual interaction and views can enhance entrances, reading rooms and areas designed for children.

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Whether designed gardens, courtyards or adjacent natural areas, open space provides a relationship to the landscape that can complement architecture.

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Shady seating areas are also desirable and can be provided under trees, or beneath a trellis, pergola or canopy.

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Water features are a desirable amenity that can add visual focus and delightful sound to a space.

Thinking about future expansion •

Public facilities are designed for long life spans during which there is usually a need to expand

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Library expansions are usually necessary to house larger collections for a growing or changing population.

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Remodelling to upgrade an existing library for compliance with new seismic and accessibility codes can also result in major modifications and an opportunity to simultaneously enlarge the structure.

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When selecting a new site, it is prudent to think beyond the immediate project at hand (which can be daunting) to 20-30 years into the future

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It is difficult for anyone to predict what the ideal library will look like in 2030. It is wise to consider expansion space, where feasible, when selecting a site today. It may accommodate new and complementary uses not envisioned by librarians and information specialists today.

Development Restrictions In more urban settings or special districts, development guidelines can define how much of the parcel is buildable and how large the building can be. Such guidelines can be obtained through the local zoning or planning office; staff can help interpret them. Outlined below are the more common restrictions that might be found. Floor Area Ratio

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Development guidelines may specify the acceptable density that can be obtained on a site.

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The most common measurement of density is floor area ratio (FAR), which measures total building area to total buildable site area. For example, a proposed library of 20,000 square feet on a site of 10,000 square feet has a FAR of 2:1.

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Jurisdictions can set FARs that encourage or discourage higher density depending on the setting and future vision for a particular district.

Setbacks

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Setbacks are buffer spaces that specify a distance back from a property line or an adjacent structure to where a new building can be located.

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Setbacks were originally developed to prevent a fire spreading across property lines from one structure to another.

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They also create yards and open space that can become desirable outdoor amenities

Easements

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Easements can apply where there are major utilities that require access for service.

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They are essentially zones within a site that cannot be built upon.

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Easements can also be required for existing or future transit.

Dedications

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Dedications are portions of a site that are required to be turned over to public land prior to development proceeding.

Height Restrictions

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Local codes and guidelines often specify a height limitation by building type or by district.

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They can define number of stories allowed or a maximum overall building height in feet.

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Height restrictions combined with required setbacks begin to define the building envelope, within which the new structure must remain.

SITE ORIENTATION

2.

SITE EVALUATION CRITERIA

Criteria 1) Geography Evaluate proximity to other civic services, schools and transit. 2) Land Acquisition Costs Compare initial cost, long-term lease cost or other arrangement. 3) Soil /Structural Implications Assess soils report and anticipated structural footings. 4) Infrastructure Estimate extent of new or modified infrastructure needs

SITE A

SITE B

(water, power, tel/data, gas, vaults, utility reroutes) 5) Topography Gage extent of site grading needed to prepare site. 6) Project Approvals Compare environmental, design and city approvals process. 7) Site Fit Check library building program on the site’s buildable area. 8) Parking Check parking requirements based on local codes and recommendations. Factor in costs for structure if needed. 9) Site Amenities Assess opportunities for accommodating gardens and gathering places.

Criteria (continued) 10) Future Expansion Check if site can accommodate future growth. 11) Development Restrictions Evaluate any development limits that affect buildable area and envelope (maximize size, height, setbacks, dedications, easements) 12) Ease of Access Assess inherent ease of pedestrian, vehicular, bicycle and service access to the site. 13) Site Features Natural views to/from site, wind and sun patterns, site’s visibility to the general public. 14) Other Considerations Unique factors based on local context and politics.

SITE A

SITE B

Accessibility and parking design

Hydrology Studies Hydrology studies are performed by environmental consultants or hydrologic engineers. The studies are based on the review of existing maps and records, as well as the collection of site- specific hydrologic measurements. The hydrology studies include: • • • • • • • •

Surface water drainage patterns (on and off site). Floodplain zones. Aquifers and recharge zones. Depth to ground water. Storm drainage system requirements. Erosion hazard areas. Debris flows and mudslides hazards. Coastal flooding and tsunami hazards.

Surface hydrology is an integral part of the slopes and subsurface drainage systems. The kinds of information normally indicated and analyzed include determination of watersheds (basically a system of ridge lines and valleys or drainage patterns), duration and volume of flow, swales, streams, standing water, and flood plain definition. Susceptibility to erosion and the problem of sedimentation to off-site water flow are also problems to be noted. Generally it is advisable to avoid disturbing natural subsurface drainage patterns such as high water tables which have implications for locations of structures or excavations

The simple definition It's the area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater.

You're sitting in a watershed now Homes, farms, ranches, forests, small towns, big cities and more can make up watersheds. Some cross county, state, and even international borders. Watersheds come in all shapes and sizes. Some are millions of square miles, others are just a few acres. Just as creeks drain into rivers, watersheds are nearly always part of a larger watershed.

Preparation of site analysis diagrams Topography and Slopes – Treatment of these factors requires base information in the form of contours and elevations to a degree of accuracy appropriate to the proposed development. For general planning, topographic information such as is available from U.S. Geological Survey quadrangle maps may be suitable. However, more detailed site design requires more specific elevations from aerial or field surveys. Visually, as well as functionally, the form of the landscape, its slopes and patterns are one of the most important categories to consider, no matter what the proposed land use. The topographic map provides a considerable amount of information including drainage patterns and problems, potential on-site and off-site views, erosion and sedimentation potential, as well as potential for development. There are standards that establish categories of slopes related to suitability for different uses and activities. These standards are somewhat regional. For example, the acceptable range of slopes in the mid-West is apt to be more restricted than that used in western Pennsylvania or West Virginia where steeper natural slopes are more prevalent. A typical slope breakdown might include: 0-2% - Most developable 2-8% - Easily accommodates most categories of development 8-16% - Some development restrictions; upper limits for roads and walks 16-24% - Significant restrictions to most development 24%+ - Generally restricted for development

Geology and Soils – General information is available from U.S.Geological Survey quadrangle maps and U.S.Department of Agriculture soil surveys. More explicit information may be required from core drillings and specific soil testing. The subsurface geology is the basis for the visible landform discussed above. Other implications are the engineering characteristics such as bearing capacity that determine suitable locations for structures and other heavy elements. Conversely, shallow depth to bedrock may restrict certain construction options on the basis of cost and impact of development. Similarly, a high water table may limit or restrict some sanitary sewage options. Closely related are the soils characteristics which are frequently a direct product of the underlying geology. The soils may be important in terms of stability, suitability for structural foundations, erosion susceptibility, surface drainage, and soil fertility to support plant growth. Again, the suitability of soils is very much dependent upon the proposed uses. A site suitable for intensive structural development may be unsuitable for recreational activities and vice-versa

Influences of topography on the natural systems of a  site: controls flow of surface water­ drainage networks controls pattern of erosion and sedimentation 

What to look for in site reconnaissance: the shape of the land­ drainage patterns and landforms (terrain  units) slopes­ steepness, cover, aspect many important aspects of land  use and site optimum slopes for parking lots, house sites, streets,  playgrounds, lawns, and so on.

Slope Constraints on Development Site with slopes averaging less than 1%: Usually result in areas of poor drainage and larger than normal gravity flow systems. Otherwise, they offer few development constraints.

Sites with slopes averaging 1 ­3%: Usually offer the least topographic constraints. Positive drainage  can normally be attained without excessive site re­grading. These 

sites are suitable for a wide range of development types;  unfortunately these are often our best farmlands.

Sites with slopes averaging 3 ­ 5%: These sites impose only slight constraints, except to  developments that require large, fairly flat surfaces, e.g. play  fields, parking areas, and major structures such as m  manufacturing plants and warehouses.

Sites with slopes averaging 5 ­ 8%: Impose slight constraints to developments with small structures  and minimal site coverage and support systems. Constraints  increase with the size of structures and with the percentage of  site covered. These slopes have a formative impact on site  organization, as well as on the orientation of buildings and roads.

Sites with slopes averaging more than 8%: Generally impose severe constraints to development. These  slopes normally exclude structures with large footprints and  severely increasing the cost of even small structures. On the other  hand, unique visual amenities often make these sites desirable  places on which to build.