Engineering the Mountains: Infrastructure Planning Tips for Colorado Land Development

When you’re developing in Colorado’s foothills or mountains, you’re not just working with the land. You’re also working within physical and regulatory constraints that can impact your timeline, your budget, and your lot yield.

Grading, fire access, water rights, and infrastructure are more complex in these areas, and skipping a step early can cost you later.

Here’s a breakdown of the key considerations, using simple rules of thumb and real-world insight we share with clients throughout the region.

Roads and Access – Start With the Site’s Backbone

• 25 to 30 percent of the site often goes to roads and right-of-way

• ROW width: 60 to 66 feet is typical

• Cul-de-sacs: 45 to 50 foot radius for fire turnaround

• Driveways: plan for slope and emergency vehicle access

"Your road layout controls everything. It sets the foundation for fire access, drainage, and lot layout."

Water Rights – Owning Land Doesn’t Mean You Have Water

• Water rights in Colorado are separate from land ownership

• Well permits are required through the Division of Water Resources

• Some sites need augmentation plans for legal water use

• Even hauled water and cisterns must be permitted and approved

"Water rights can make or break a project. Confirm your source before investing in design or entitlements."

Water, Septic, and Drainage – Every Site Is Different

Water

• 6 to 8 inch mains are needed for fire flow

• Hydrant spacing: 400 to 500 feet

• Most mountain sites rely on individual wells

Septic

• Individual systems are common

• Design depends on percolation, slope, and separation distances

Stormwater

• 15 to 25 percent of the site is often needed for detention or infiltration

• Use 3 to 1 side slopes and 1 to 2 feet of freeboard

• Consider rock swales, infiltration trenches, and erosion control at outlets

"Each home may need its own system, but the land still needs to drain as one coordinated site."

Fire Flow – Hydrants or Cisterns?

With water mains:

• 8 inch pipe is required

• Hydrants spaced every 400 to 500 feet

• System may need to be looped or pressurized

Without water mains:

• 10,000 to 30,000 gallon cisterns are typical

• Must be located within 1,000 feet of homes

• Access, signage, and Storz fittings required

• Often placed in open space with dedicated easement

"Most mountain subdivisions rely on cisterns. If hydrants aren’t feasible, plan early for fire district approval."

Grading and Earthwork – Work With the Land, Not Against It

• Minimum 2 percent slope away from buildings

• Avoid slopes steeper than 3 to 1 unless reinforced

• Balance cut and fill to avoid hauling

• Coordinate grading and utility depth from the start

"Forcing flat grading on steep terrain leads to high costs. Let the site guide your design."

Dry Utilities – Trenching, Routing, and Easements

• Trench depth: 30 to 36 inches

• Easement width: 15 to 20 feet is typical

• Steep or rocky terrain may require separate corridors

• Joint trenching is possible on flatter ground

"Plan utility routing early. Delays and conflicts here are a common cause of project slowdowns."

Sidewalks, Mailboxes, and Open Space – The Small Stuff Adds Up

• Sidewalks: often optional, but 5 feet wide when required

• Mailboxes: cluster mailboxes required by USPS

• ADA ramps: required if sidewalks or crossings are installed

• Trails and open space may be required under zoning or PUDs

"Even a short walking path or community space can strengthen a site plan and appeal to buyers."

How the Land Really Breaks Down

Use	Rule of Thumb
Roads and Right-of-Way	25 to 30 percent
Stormwater Management	15 to 25 percent
Open Space or Natural Area	10 to 15 percent
Buildable Lots	35 to 50 percent

"A 10-acre mountain site rarely yields 10 acres of lots. The goal is to make the most of the land that is actually usable."

Planning a Mountain Project? Let’s Get It Right From the Start

Mountain development requires a different mindset than flat land subdivision. At Land Pro Civil, we help clients take the guesswork out of complex sites through clear planning and efficient civil design.

If you're considering a project in the foothills or mountains of Colorado, we can help you plan with confidence and move forward with less risk.

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