Following the results of the initial evaluation, PPG 16 offers two solutions for preserving any significant archaeological deposits found to be on a development site. The first, and explicitly preferred, method involves preservation in situ whereby the archaeology is left untouched beneath a new development through methods such as adaptation of foundation design and architectural layout of the proposed new development, or by raising the level of the development with made ground so that its foundations do not reach the archaeological horizon.
If preservation in situ is not feasible then PPG 16 permits preservation by record. This involves archaeological fieldwork to excavate and record finds and features (thereby destroying them). This may involve a full strip map and sample excavation, further trenching or an archaeological watching brief which involves an archaeologist monitoring groundworks for the new development and recording any finds or features revealed.
All forms of archaeological investigation undertaken through PPG 16 are funded by the developer through an extension of the Polluter Pays principle, although this is not made explicit in the document itself. The work is usually undertaken to satisfy a planning condition placed on an application for development although PPG16 prefers evaluation to take place in advance of any planning decision. A developer tenders for the work to be done and chooses an archaeological organisation to retain. The work is monitored by a curator, normally the County Archaeologist, who is nominated by the local planning authority as an advisor and who also identifies sites where archaeology might be threatened by development. Following submission of a satisfactory site report and demonstration that a site's archaeological potential has been properly safeguarded and/or recorded, the curator will usually advise that development can continue.
Curators maintain a Sites and Monuments Record or SMR, a database of known archaeological sites which is often used to inform decisions on archaeological potential.
Critics of PPG 16 argue that the commercialisation of UK archaeology has resulted in more work of lower quality being undertaken; there is a certainly a liability of unpublished site reports and homeless site archives awaiting resolution. The competition for work amongst archaeologists, and the fact that the developers funding them have no real use for their final product, also tends to drive prices down meaning that wages and conditions for archaeologists in the UK are generally far below the national average.
PPG 16 is only guidance information to planners and does not have the full force of law. Its precepts can be enforced through the Town and Country Planning Act and ultimate decisions on its implementation rest with the Secretary of State however, without full legal status it lacks the power and reach of measures safeguarding similar environmental issues which are enshrined in law, such as those concerning endangered species.