Home / Insights / Evidence you can rely on

Pricing a fixed-fee survey when you cannot see the ground: where to spend field days

For bid managers and survey coordinators pricing 2027 survey work at environmental and engineering consultancies

Price the bid in field days, and let a desk read decide where those days go before you fix the number. Then spend them on the stretches the records flag, inside the window each survey type needs.

By the Vireo teamPublished 10 November 202611 minute readSources checked 10 November 2026

Fixed-fee survey pricing: where to spend field days | Vireo

Key points

The Scottish Peatland Survey guidance (2017) sets a low-resolution grid of "Usually 100 m X 100 m" and detailed probing "at 10 to 50m intervals" along tracks.
NatureScot standing advice (updated August 2024) puts the ideal water vole survey period at "June to August", three months of the year.
A report more than three years old "is unlikely to still be valid", says the CIEEM advice note on the lifespan of ecological reports and surveys (April 2019).

Your fixed-fee bid rests on one line you cannot yet see: field days. The CIEEM Guidelines for Preliminary Ecological Appraisal (second edition, December 2017) give the order of work in section 2.1: "It is advisable, in most cases, to undertake the desk study first, as this can inform the scope of the field survey."

Field days are the scarce unit

The people who can do the fieldwork are short, so the field day is the unit to price and protect. The CIEEM report Ecology Skills and Capacity in Ireland reports on its professional cohort. It says: "45% of respondents noted that their organisation is incapable of meeting project demand due to staff and skills shortages."

The report is undated and draws on 2025 surveys of 136 participants and 14 interviews. It states that "Field surveying is the clearest skill gap." One private sector consultant told the researchers: "I'm turning away work on a weekly basis."

The UK picture has the same shape. In its 2025 State of the Profession survey announcement (29 May 2025), CIEEM reports "a noticeable shortage of suitably experienced people for the more senior roles available". It also refers to "the main ecological field survey season between April and October".

45 per cent

Against: of professional respondents say their organisation cannot meet project demand
Source: CIEEM, Ecology Skills and Capacity in Ireland
Date: Checked 10 Nov 2026

April to October

Against: the main ecological field survey season
Source: CIEEM, State of the Profession survey, 29 May 2025
Date: Checked 10 Nov 2026

18 months

Against: the age after which a site visit is needed before a report is relied on
Source: CIEEM advice note on report lifespan, April 2019
Date: Checked 10 Nov 2026

The Irish report adds two lines every bid manager will recognise. "Survey work can become concentrated into short periods of time", and "The seasonal constraints on survey work are not always recognised by the wider project team".

No source opened for this article publishes a fee, a day rate or an overrun figure. So this guide works in field days.

What does a desk read settle before the bid?

A desk read settles three things before you price. They are the survey types the site is likely to need, where each one applies, and the season each must fall in. The professional guidance for ecology, heritage and peat all puts the desk work first.

Ecology

The CIEEM appraisal guidelines say "A PEA normally comprises a desk study and a walkover survey" (section 1.2). They also warn, in section 1.6, that "In the majority of cases, additional surveys beyond the PEA will be required." Those additional surveys are the days a fixed fee tends to miss.

The CIEEM Guidelines for accessing, using and sharing biodiversity data in the UK (October 2023) say data "helps ecologists to plan and target surveys accordingly" (section 3.2). Section 2.2 adds the caution that governs every desk read: "absence of evidence is not the same as evidence of absence."

Heritage

The CIfA Standard and guidance for historic environment desk-based assessment (December 2014, updated 1 October 2020) looks ahead to fieldwork. It asks for strategies for further evaluation where the resource "is not sufficiently well defined".

Paragraph 3.3.6 requires that "All sources consulted should be listed in the report, whether or not they have been productive." Paragraph 3.3.9 expects a visit to the study area "Unless access is restricted". Allow for that visit in the day count.

Peat

The Scottish Peatland Survey guidance starts its flowchart with a desk study: "Review existing site information". The whole-site survey follows, and the layout is then set "avoiding areas of peat identified by site surveys".

Table 1 of the same guidance states that "Greater intensity surveys will not be required for areas that are unlikely to be developed." The detailed survey is a "Targeted sampling regime tailored to potential development areas".

Survey windows by survey type in Scotland

Each survey type has its own window, and the window sets how many working days exist to sell. The table is Scotland only: it uses NatureScot standing advice. Check the advice for your own nation before you fix dates.

Survey type (Scotland)	Window	Best period	Normally stays valid for
Great crested newt, breeding ponds	March to June	eDNA sampling: mid April to June	Two more survey periods
Great crested newt, terrestrial habitat	March to September	Not stated	Two more survey periods
Water vole	April to October (May to September in upland locations)	June to August	Two more survey periods
Reptiles	April to September	April, May and September	Two more survey periods
Bat activity, wind farm collision risk	April to October	Not stated	Two more survey periods
Otter	Any time of year	Not after prolonged heavy rainfall or high water	Two years
Badger	Any time of year	February to April	Two years

Table 1. Scotland only. Survey windows and validity periods for seven survey types in NatureScot standing advice. Source: NatureScot standing advice for planning consultations on great crested newts, water voles, bats, otters and badgers (each updated August 2024), and on reptiles (undated). These windows are not advice for England, Wales, Northern Ireland or Ireland.

NatureScot also publishes an Ecological survey calendar that marks each month as optimal, limited or not possible. It says the calendar "should be used as a reference guide only", because "site and project specific circumstances may alter seasonal windows."

Weather takes days out of every window. The otter advice notes that "Heavy frost or recent snow can also make finding spraints difficult." Count the working days you can rely on, then hold some back.

How long does survey evidence last?

Survey evidence has a shelf life, and a programme that slips can turn priced days into repeat days. The CIEEM advice note on the lifespan of ecological reports and surveys (April 2019) gives four age bands.

Less than 12 months: "Likely to be valid in most cases."
12 to 18 months: likely to be valid in most cases, with exceptions that include mobile species.
18 months to 3 years: "A professional ecologist will need to undertake a site visit and may also need to update desk study information."
More than 3 years: "The report is unlikely to still be valid and most, if not all, of the surveys are likely to need to be updated."

Species advice can be tighter or looser than the general note, and it differs by nation. NatureScot says great crested newt surveys "normally remain valid for two more survey periods". Natural England says, in Great crested newts: advice for making planning decisions (updated 7 April 2025), that data "should be no older than 4 survey seasons."

For the bid, this means one more line. State the season each survey is priced for, and state what happens to the fee if the client moves the programme past it.

Illustrative example

This route is invented. It is a 30 km cable route across mixed farmland and upland edge, priced in January for the 2027 season. One two-person team is available for 12 working days in the window.

The team lead assumes a detailed walkover covers 2 km of route in a day. That figure is an assumption of this example. Use your own.

Price the full route

30 km divided by 2 km a day is 15 field days. The window holds 12. The full walkover is 3 days over before any weather is lost.

Run the desk read

The records, maps and imagery flag 8 km to walk first: watercourse crossings, mapped peat and possible heritage features. That is 27 per cent of the route.

Price the targeted share

8 km divided by 2 km a day is 4 field days. The plan fits the window with 8 days spare for weather, access delays and return visits.

Count the peat probing

Say 3 km of the 8 km crosses mapped peat. Borrowing the track spacing in the Scottish guidance as an illustration, the 50 m end gives 60 probe positions on the centreline. At 10 m it is 300, before the "10m right angled offsets".

Figure 1. Field days on an invented 30 km route at an assumed 2 km a day for one team. Vireo arithmetic. The productivity figure is an assumption of the example and comes from no published rate.

The targeted walkover covers the lengths the desk read flags first. The other 22 km is surveyed as the scope and the guidance require, and the bid prices that work as its own line.

So the bid carries two lines: 4 days of targeted walkover on the named 8 km, and the survey of the remaining 22 km at its stated intensity. If the first visit finds more, the client has already seen the basis for the change.

Pricing a route with a short window and one senior team? Send us your route and we reply within two working days.

Try it

Field day calculator

Enter your own route and your own productivity figure. The result shows field days for the whole route and for the targeted share, and whether each fits your window.

What you are pricing

Route length (km)

Share the desk read flags to walk first (per cent, your own figure)

Kilometres one team covers in a day (your own figure)

Number of teams

Working days available in the season window

Every productivity figure here is your own assumption. No published rate is applied. The targeted share is where the walkover starts. The remaining length is surveyed as your scope and the guidance require. The targeted length is rounded to the nearest whole kilometre or hectare, and field days are rounded up to whole days. Take the window for each survey type from the table above or from the advice that applies to your site.

Send us your route with these numbers

Where to spend the field days

Spend the first field days where a finding would change the route, the method or the season. The order below follows the guidance already quoted.

Narrowest window first. A survey with a three month best period goes in the diary before one that can run all year.
Where sources disagree. CIfA asks for "an assessment of their relevance and reliability". A stretch where two records conflict needs eyes on it.
Where the design can still move. The peat guidance sets the layout after the first survey, so walk the ground that could shift the line.
Where the record is silent. Absence of evidence is not evidence of absence. A blank on the map earns a short check, in proportion to the risk.
Senior people on judgement, not distance. With senior staff short, give them the flagged stretches and the sign-off.

The Vireo Corridor Evidence Pack is a desk read of a linear route before survey. The illustrative 30 km corridor example on our site narrows 1,240 unlisted anomalies to a first ten. Its message is "walk 8 km, not 30".

Every figure in a pack carries its range, its source and its test label, so the day count in your bid has a reference behind it. Coverage is the UK and Ireland. Vireo can also supply the surveys: drone, aerial and ground, including ground-penetrating radar and magnetometry.

What to do next

List the survey types and their windows

Use the table above, or the standing advice for your nation. It costs nothing but an hour and it sets the diary.

Count the working days you can rely on

Take out leave, other bids and a weather allowance. Write the number down.

Run the arithmetic both ways

Use the calculator with your own productivity figure. Keep both results for the bid file.

Write the assumption into the bid

Name the stretches walked first, how the remaining length is surveyed, the season priced for, and what triggers a change.

Get the desk read before you fix the number

Do it in house from the records, or commission one.

Frequently asked questions

Can a preliminary appraisal report go in with the planning application?

Not normally. Section 1.5 of the CIEEM guidelines says: "Under normal circumstances it is not appropriate to submit a PEAR in support of a planning application."

Is there a published rate for kilometres walked in a day?

None of the sources opened for this article gives one. Use your own records from past jobs on similar ground, and state the figure in the bid.

Sources

Ask the team

Written by the Vireo teamVireo Nature reads land before anyone surveys it. Every figure in our work carries its range, its source and its test.

Working on something like this?Send us your route

Three details. The team checks coverage and fit, and replies within two working days.

Send us your route

Live exampleInside a site

Tap real peat, river, habitat and ground motion data, read by the Vireo Neural Map.

Explore the live map