A row of wood-framed two-story homes under construction behind a block wall lined with young trees, with a dry grass field in front and mountains under a blue sky.

Representative photo — not the project site.

Residential subdivision

Orchardcrest Subdivision

Property and boundary surveys, subdivision improvement plans and construction staking for a residential subdivision near Oroville, plus final subdivision maps for multiple phases.

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The project

Orchardcrest Estates is a phased residential subdivision in the Thermalito area of unincorporated Butte County, north of Highway 162 and just west of the Oroville city limits.

American Engineering provided property and boundary surveys, subdivision improvement plans and construction staking for a residential builder, plus final subdivision maps for multiple phases.

County records describe Orchardcrest Estates as a phased development, with an earlier phase of homes south of the land that remained. In January 2024 the Butte County Planning Commission approved a tentative subdivision map for that remaining land and called for a further Public Works review of a drainage issue. County records list another engineering firm as that map's applicant. These public records do not identify which Orchardcrest phases American Engineering's work covered.

The same records describe the remaining land as flat former orchard ground between 10th Street and Middlehoff Lane, zoned Medium Density Residential and bordered mostly by single-family homes. The records name the Thermalito Water and Sewer District as its water and sewer provider, and FEMA's flood maps place the site in Zone X, an area of minimal flood hazard, on FIRM panel 06007C0790E (January 6, 2011).

Scope

Our scope

American Engineering's work, grouped by step:

  1. Survey the property

    • Property and boundary surveys

    Locating the property lines and corner monuments that design and mapping build on. See boundary surveying.

  2. Prepare subdivision improvement plans

    • Streets
    • Water
    • Sewer
    • Storm drain
    • Storm drain detention basin improvements

    The construction drawings for a subdivision's public improvements. See improvement plans.

  3. Provide construction staking

    • Construction staking

    Setting line and grade in the field for curbs, pipes and pads from approved plans. See construction staking.

  4. Prepare the final maps

    • Final subdivision maps for multiple phases

    The maps that create a subdivision's lots once recorded. See parcel and subdivision maps.

Technical highlights

How the work fits together

Three illustrative diagrams of typical phased subdivision work.

A subdivision mapped in phases

A phased subdivision is typically mapped and improved in stages. One boundary survey retraces the tract's corners; each phase then gets its own final map, and its streets and pipes are built to the phase line, ready for the next phase to extend. Storm drains carry street runoff to a detention basin, which lets it out slowly to an existing storm drain. Building the basin and downstream pipes in an early phase lets later phases drain into them.

One tract, mapped and improved in phases

Illustrative diagram — not to scale

Schematic of a residential tract developed in phases, draining to a detention basin Plan view of a rectangular tract beside an existing road and side street, shaded by phase and labelled first, next and later phase. Two interior streets joined at one end form a loop lined with lots. Blue storm drain lines run from street inlets in the later phases back through the first phase to a detention basin lot in its corner, which drains through a metered outlet to an existing storm drain under the road. Triangles mark boundary monuments at the tract corners. Illustrative only, not the actual layout. First phase Next phase Later phase Basin Existing road Existing storm drain 1 2 3 4 5
  1. Boundary monuments at the tract corners. The boundary survey retraces them, and each phase's final map ties to them.
  2. A phase line. Each phase gets its own final map, all within one approved tentative map.
  3. Streets and storm drain cross the phase lines, so each phase is designed to connect to the next.
  4. Drop inlets collect street runoff, and storm drain lines carry it back through the earlier phases to the basin.
  5. The detention basin holds runoff and lets it out through a small metered outlet to an existing storm drain.
Generic schematic, not the actual Orchardcrest layout. The number of phases, the lots, streets, and the basin's location and outlet are illustrative, not survey or design data.

What a detention basin does

Roofs and paving shed runoff faster than the field or orchard they replace. A dry detention basin stores that runoff during a storm and releases it through a small outlet, so the peak flow leaving the site drops. Agencies commonly cap the release at the pre-development peak and expect an overflow path in case the outlet plugs. On their own, dry basins do little to reduce runoff volume.

A dry detention basin, and what it does to peak flow

Illustrative diagram — not to scale

Basin section

Section through a dry detention basin with its inlet, outlet structure and emergency overflow Cross-section of a flat-bottomed basin cut into level ground. A street drop inlet feeds a pipe into the basin, which holds water up to a dashed design water level, with freeboard between that level and the top of the bank. At the low end, an outlet structure with a small low-flow opening at floor level and an open top drains through a pipe below the floor toward a storm drain, and an arrow shows emergency overflow passing over the bank. Illustrative, not project drawings. Street Freeboard To storm drain 1 2 3 4
  1. A street drop inlet and pipe carry runoff into the basin.
  2. In a storm the basin fills toward its design water level, then drains dry.
  3. The outlet structure meters the release through a small low-flow opening; bigger storms also spill over its open top.
  4. Freeboard above the design water level, and an emergency overflow over the bank, handle a plugged outlet or a larger storm.

Runoff over time

Hydrograph of runoff before development, after development without detention, and with detention A graph of flow against time with three curves. The before-development curve has a low, broad peak, and a horizontal line at that peak marks the allowable release. The after-development curve without detention rises to a much taller, sharper peak. The with-detention curve peaks just below the allowable line and stays up longer. Illustrative only. Flow Time Allowable peak 1 2 3
  1. Before development: a low, broad peak that sets the allowable release.
  2. After development, without detention: roofs and paving send a taller, sharper peak downstream.
  3. With detention: the peak stays at or below the allowable release and spreads over a longer time. The runoff volume is about the same.
Detention stores runoff and releases it slowly, so peak flow downstream does not increase. Illustrative only, not project drawings or calculations: basin shapes, outlets and release rates vary by agency and site.

What goes into a subdivision street

Subdivision improvement plans set a street's surface and what runs beneath it. Pavement over aggregate base sits between curb, gutter and sidewalk. Pressurized water mains can run shallower and feed fire hydrants. Storm drains pick up gutter flow at drop inlets. Sanitary sewers usually sit deepest so house laterals can drain to them by gravity, with manholes for access. Widths, depths and positions follow each agency's standards.

A typical subdivision street in cross-section

Illustrative diagram — not to scale

Cross-section of a typical subdivision street with water, storm drain and sewer lines A street cross-section between right-of-way lines: sidewalk and curb and gutter on each side of crowned pavement over aggregate base. Below grade, a shallow water main feeds a fire hydrant behind the curb, a drop inlet at the gutter drains to a larger storm drain at mid-depth, and the deepest pipe, the sanitary sewer, has a manhole to the surface and a house lateral sloping in from the lot. Illustrative only. R/W R/W Street Water Storm drain Sewer Lateral 1 2 3 4
  1. Pavement over aggregate base, with curb, gutter and sidewalk inside the right-of-way (R/W).
  2. A water main, the shallowest of the three pipes, feeds a fire hydrant behind the curb.
  3. A drop inlet at the gutter drains to the storm drain.
  4. The sewer main runs deepest, with a manhole for access and a house lateral sloping in from the lot.
Typical section: widths, depths and utility positions vary by agency. Illustrative only, not project drawings.

Engineering considerations on phased subdivisions

  • Phases that stand alone

    Each phase's water, sewer and storm drain must work on its own yet fit the full build-out, so water loops, hydrant coverage and basin volume are planned ahead.

  • Tying into earlier work

    A new phase connects to pipe stubs, street ends and monuments left by an earlier one, so their built locations and elevations are field-checked before design and staking.

  • Little fall on flat ground

    On flat valley land, gravity sewer and storm drain lines have little natural fall, so pipe slopes, invert elevations and the basin outlet are coordinated closely.

  • Maps that close and tie

    Each final map must close on the retraced boundary, tie to earlier phases and pass the county surveyor's technical check, with durable monuments later surveyors can find.

Permits & approvals

Regulatory context

State law sets how a phased subdivision is mapped, and county staff recommended conditions for the remaining Orchardcrest land. They describe the public process and the 2024 map, not American Engineering's scope.

  • Gov. Code §66456.1 · §66452.6

    Several final maps, one tentative map

    The Subdivision Map Act lets a subdivider file multiple final maps on one approved tentative map, if the subdivider says so when filing it or the agency later agrees. Filing a final map on part of it does not invalidate the rest, but each must be filed before the tentative map expires. SB 1169 (2026) lengthens tentative map life starting January 1, 2027.

  • Gov. Code §66442 · §66495

    County surveyor's check and monuments

    In an unincorporated area, the county surveyor signs each final map, stating that the subdivision is substantially the same as the tentative map and any approved alterations, and that the surveyor is satisfied the map is technically correct. The survey behind it must set enough durable monuments for another surveyor to readily retrace it.

  • General Plan Policy CIR-P6.3

    County review, city street standards

    The remaining land is unincorporated but inside the City of Oroville's sphere of influence. Under this county policy, the recommended conditions for the 2024 map call for City of Oroville improvement standards on the 10th Street and Middlehoff Lane frontages and interior streets, with road and drainage plans going to Butte County Public Works.

  • Staff report · Jan. 25, 2024

    No increase in peak flow

    The same recommended conditions require an engineered drainage plan: runoff detained on site and/or carried to the nearest natural or publicly maintained drainage channel or facility, developed peak flow no greater than before development for all storm events, the built basin's volume confirmed by topographic survey, and a funded maintenance entity. Adopted conditions may differ.

Conditions vary by agency and by map. Construction that disturbs one acre or more, or less than an acre as part of a larger common plan of development that disturbs one acre or more, also needs coverage under the State Water Board's Construction Stormwater General Permit, currently Order 2022-0057-DWQ.

  • Land Surveying

    Boundary Surveying

    Property and boundary surveys for the subdivision.

  • Civil Engineering

    Improvement Plans

    Street, water, sewer, storm drain and detention basin improvement plans.

  • Land Surveying

    Construction Staking

    Construction staking for the subdivision.

  • Land Development

    Parcel & Subdivision Maps

    Final subdivision maps for multiple phases.

See all past work

Sources

Public records and agency pages behind the project context above. The scope section describes American Engineering's own work.

  1. Planning Commission agenda, January 25, 2024: Orchardcrest Estates tentative subdivision map (Butte County)
  2. Planning Commission staff report and recommended conditions of approval, Orchardcrest Estates (January 25, 2024) (Butte County Department of Development Services)
  3. Initial Study / Mitigated Negative Declaration, Orchardcrest Estates tentative subdivision map (October 2023, PDF) (Butte County, via CEQAnet)
  4. Planning Commission action minutes, January 25, 2024 (Butte County)
  5. Flood Insurance Rate Map panel 06007C0790E, effective January 6, 2011 (ZIP download) (FEMA Flood Map Service Center)
  6. Government Code §66456.1: multiple final maps (California Legislative Information)
  7. Government Code §66452.6: tentative map expiration (California Legislative Information)
  8. SB 1169, Subdivision Map Act: tentative maps: expiration dates (bill history) (California Legislative Information)
  9. Government Code §66442: county surveyor's certificate on final maps (California Legislative Information)
  10. Government Code §66495: monuments for final and parcel maps (California Legislative Information)
  11. Stormwater Best Management Practice: Dry Detention Ponds (PDF) (U.S. Environmental Protection Agency)
  12. Construction Stormwater Program (State Water Resources Control Board)

Last reviewed .

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Subdivisions & site development

Planning a similar project?

Send the parcel location, any conditions of approval you have, and how you plan to phase the work. We'll confirm the surveys, plans, staking and maps you need.

Request a quote See more past work